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Grade 4 math worksheets

Build your own math worksheets from 35,000+ problems for grades 3 to 12, from fractions to AP Calculus. Every problem comes with step-by-step solutions.

Generate shape and number patterns

Learning goals

  • Identifies a rule governing the pattern.
  • Generates the next terms by applying the pattern rule.
  • Describes relationships among successive terms or figures.
  • Uses the rule to predict or generate additional cases.

Click problems to add them to your worksheet.

Generate shape and number patterns 1
Panels 1 through 4 show a repeating shape pattern. What shape should appear in panel 5? State the repeating rule.
Figure for problem 554395

Hints

- Compare each panel with the panel two places later. - Look for a short block of shapes that repeats.

Solution

1. The shapes alternate square, triangle, square, triangle. 2. Therefore, panel 5 should contain a square.

Answer

Panel 5 should be a square. The rule repeats square, triangle.
Generate shape and number patterns 2
In this number wall, each brick above two others shows the sum of the bricks directly beneath it. What number belongs in the empty brick?
Figure for problem 558855

Hints

- Think of combining two piles of blocks into one pile. - How could you check that the number you choose follows the wall's rule?

Solution

1. The bottom bricks show \(4\) and \(3\). 2. Their sum is \(4 + 3 = 7\), so the top brick is \(7\).

Answer

\(7\).
Generate shape and number patterns 3
Fill in the missing number in the pattern and state the rule: \(5, 9, 13, \square, 21\).

Hints

- Compare two neighboring numbers that are already filled in. - Check whether the same change works elsewhere in the pattern. - Test your missing value against the number after it.

Solution

1. Each number is \(4\) more than the one before it. 2. After \(13\) comes \(13 + 4 = 17\), and \(17 + 4 = 21\) confirms the rule.

Answer

\(17\); add \(4\) each time.
Generate shape and number patterns 4
This is a product wall. Each brick above two others shows the product of the bricks directly beneath it. Find the number in the empty brick.
Figure for problem 558871

Hints

- Imagine a rectangular array with the bottom numbers as its row and column counts. - How could you count all the dots in that array without counting them one by one?

Solution

1. The two bottom bricks are \(3\) and \(4\). 2. Multiply: \(3 \times 4 = 12\). The top brick is \(12\).

Answer

\(12\).
Generate shape and number patterns 5
These dot pictures grow in a pattern. How many dots should the next picture have? Explain the change.
Figure for problem 558878

Hints

- Count the dots in each picture in order. - What new part appears from one picture to the next? - Continue the same change one more time.

Solution

1. The pictures have \(2,4,6\) dots. 2. Each new picture adds two dots, so the next one should have \(6 + 2 = 8\) dots.

Answer

\(8\) dots; add \(2\) each time.
Generate shape and number patterns 6
In this addition wall, each brick shows the sum of the two bricks directly below it. Find the missing number in the bottom row.
Figure for problem 558882

Hints

- Think of the top brick as the total of two parts. - What is already known about one of those parts? - Use the opposite operation to find the missing part.

Solution

1. The top is \(14\), and one bottom brick is \(9\). 2. The missing brick is \(14 - 9 = 5\).

Answer

\(5\).
Generate shape and number patterns 7
A tile border begins: ○ □ □ ○ □ □ ○ □. What are the next two shapes? Which group repeats?

Hints

- Look for a place where the same sequence begins again. - Point to the shapes in one complete repeating group.

Solution

1. The repeating group is circle, square, square. 2. The last shown square is the first after a circle. The next two shapes are a square and then a circle.

Answer

□, ○. The group ○ □ □ repeats.
Generate shape and number patterns 8
Find a simple rule that fits every shown top-to-bottom input-output pair. Then use that rule to complete the table. <table> <tr> <td>\(1200\)</td><td>\(5000\)</td><td>\(15{,}000\)</td><td>\(100{,}000\)</td><td>\(240{,}000\)</td><td>\(600{,}000\)</td> </tr> <tr> <td>\(3700\)</td><td>\(7500\)</td><td>\(17{,}500\)</td><td>\(102{,}500\)</td><td></td><td></td> </tr> </table>

Hints

- Compare a known top number with the number below it. - Determine whether the same amount is added each time. - Test your rule on every completed column before using it.

Solution

1. Compare the first pair: \(3700 - 1200 = 2500\). 2. The rule \(+2500\) works for the other known pairs: \(5000 + 2500 = 7500\), \(15{,}000 + 2500 = 17{,}500\), and \(100{,}000 + 2500 = 102{,}500\). 3. Apply the rule to the missing entries: \(240{,}000 + 2500 = 242{,}500\) and \(600{,}000 + 2500 = 602{,}500\).

Answer

One simple rule that fits: add \(2500\) Missing numbers: \(242{,}500\) and \(602{,}500\)
Generate shape and number patterns 9
Find a simple rule that fits every shown top-to-bottom input-output pair. Then use that rule to complete the table. <table> <tr> <td>\(15\)</td><td>\(60\)</td><td>\(200\)</td><td>\(1000\)</td><td>\(3000\)</td><td>\(12{,}000\)</td> </tr> <tr> <td>\(45\)</td><td>\(180\)</td><td>\(600\)</td><td>\(3000\)</td><td></td><td></td> </tr> </table>

Hints

- Compare a top number with the number below it. - Find the factor that changes \(15\) into \(45\). - Check that the same multiplication rule works for the larger numbers.

Solution

1. Compare the first pair: \(15 \times 3 = 45\). 2. The rule \(\times 3\) works for the other known pairs: \(60 \times 3 = 180\), \(200 \times 3 = 600\), and \(1000 \times 3 = 3000\). 3. Apply the rule to the missing entries: \(3000 \times 3 = 9000\) and \(12{,}000 \times 3 = 36{,}000\).

Answer

One simple rule that fits: multiply by \(3\) Missing numbers: \(9000\) and \(36{,}000\)
Generate shape and number patterns 10
Using a simple regular factor rule that fits the shown rows, continue the pattern with two more equations. Calculate every product, and describe how the products change. \(4\times 70=\square\) \(8\times 70=\square\) \(12\times 70=\square\) \(16\times 70=\square\)

Hints

- Notice how the first factor changes. - Check whether the second factor changes. - Compare consecutive products. - Connect the change in the factor to the change in the product.

Solution

1. The first four products are \(280,560,840,1120\). 2. The first factor increases by \(4\), while the second factor stays \(70\). 3. The next equations are \(20\times 70=1400\) and \(24\times 70=1680\). 4. Each product increases by \(4\times 70=280\).

Answer

\(20\times 70=1400\) \(24\times 70=1680\) The products increase by \(280\) each time.
Generate shape and number patterns 11
Calculate each row. What pattern do you notice among the quotients within each row? a) \(240\div 4\), \(120\div 4\), \(60\div 4\) b) \(600\div 6\), \(300\div 6\), \(150\div 6\) c) \(800\div 8\), \(400\div 8\), \(200\div 8\)

Hints

- Track how the dividend changes within each row. - Check whether the divisor changes. - Compare each quotient with the previous quotient. - State exactly how the quotients change.

Solution

1. Part a gives \(60,30,15\). 2. Part b gives \(100,50,25\). 3. Part c gives \(100,50,25\). 4. In each row, the dividend is halved while the divisor stays fixed, so the quotient is also halved.

Answer

a) \(60,30,15\) b) \(100,50,25\) c) \(100,50,25\) In each row, halving the dividend halves the quotient.
Generate shape and number patterns 12
Write the next division equation. Explain which number stays the same and how the other two change. \(24{,}000\div6=4000\) \(30{,}000\div6=5000\) \(36{,}000\div6=6000\) \(42{,}000\div6=7000\)

Hints

- Compare the numbers in the same position in successive equations. - Which part of an equation does not change? - Use a multiplication check for your predicted next line.

Solution

1. The divisor is always \(6\). 2. Each dividend increases by \(6000\), so the next is \(42{,}000+6000=48{,}000\). 3. Each quotient increases by \(1000\), so the next is \(8000\). 4. The next equation is \(48{,}000\div6=8000\).

Answer

\(48{,}000\div6=8000\).
Generate shape and number patterns 13
Give a simple regular rule that fits all the shown terms, then use that rule to continue the number pattern with three more numbers. \(125{,}400, 126{,}100, 126{,}800, 127{,}500, \ldots\)

Hints

- Find the difference between the first two terms. - Check whether the same difference appears again. - Apply the repeated change three times.

Solution

1. The difference between consecutive terms is \(700\). 2. Add \(700\) to get \(127{,}500 + 700 = 128{,}200\). 3. Continue: \(128{,}200 + 700 = 128{,}900\). 4. Continue again: \(128{,}900 + 700 = 129{,}600\).

Answer

Next numbers: \(128{,}200, 128{,}900, 129{,}600\) One simple rule that fits: Add \(700\) each time.
Generate shape and number patterns 14
Continue counting by \(500\) until you reach \(351{,}000\). \(348{,}000, 348{,}500, \ldots, 351{,}000\)

Hints

- Add \(500\) to each term. - Watch how the hundreds and thousands digits change at each full thousand. - Stop when you reach the target number.

Solution

1. Add \(500\) repeatedly. 2. The missing terms are \(349{,}000\), \(349{,}500\), \(350{,}000\), and \(350{,}500\). 3. One more step gives \(350{,}500 + 500 = 351{,}000\).

Answer

\(348{,}000, 348{,}500, 349{,}000, 349{,}500, 350{,}000, 350{,}500, 351{,}000\)
Generate shape and number patterns 15
Find the step size and direction in each pattern. Then write the next three terms. a) \(456{,}700, 456{,}800, 456{,}900, \ldots\) b) \(820{,}000, 810{,}000, 800{,}000, \ldots\)

Hints

- Compare the first two terms in each pattern. - Decide whether the pattern increases or decreases. - Pay attention to changes across a full thousand or hundred thousand.

Solution

1. For a), each term increases by \(100\). 2. The next three terms are \(457{,}000\), \(457{,}100\), and \(457{,}200\). 3. For b), each term decreases by \(10{,}000\). 4. The next three terms are \(790{,}000\), \(780{,}000\), and \(770{,}000\).

Answer

a) Step: \(+100\); next terms: \(457{,}000, 457{,}100, 457{,}200\) b) Step: \(-10{,}000\); next terms: \(790{,}000, 780{,}000, 770{,}000\)
Generate shape and number patterns 16
Count backward from \(1{,}000{,}000\) by \(1000\) until you reach \(994{,}000\). Write the complete sequence.

Hints

- Remove one thousand at each step. - Pay attention to the first change from \(1{,}000{,}000\) to a six-digit number. - Stop at the stated target.

Solution

1. Begin at \(1{,}000{,}000\). 2. Subtract \(1000\) repeatedly to get \(999{,}000\), \(998{,}000\), \(997{,}000\), \(996{,}000\), \(995{,}000\), and \(994{,}000\).

Answer

\(1{,}000{,}000, 999{,}000, 998{,}000, 997{,}000, 996{,}000, 995{,}000, 994{,}000\)
Generate shape and number patterns 17
Fill in the missing numbers in this counting pattern. \(599{,}996, \square, \square, 599{,}999, \square, 600{,}001, \square\)

Hints

- Determine the distance between the given terms. - Adding \(1\) to a number ending in several nines changes multiple places. - Identify the number exactly between \(599{,}999\) and \(600{,}001\).

Solution

1. The pattern counts forward by \(1\). 2. The first two missing numbers are \(599{,}997\) and \(599{,}998\). 3. The number between \(599{,}999\) and \(600{,}001\) is \(600{,}000\). 4. The number after \(600{,}001\) is \(600{,}002\).

Answer

\(599{,}997, 599{,}998, 600{,}000, 600{,}002\)
Generate shape and number patterns 18
Find the rule and write the next two equations. \(120 \div 6 = 20\) \(240 \div 6 = 40\) \(360 \div 6 = 60\) ... ... How do the dividend and quotient change each step?

Hints

- Find the change between consecutive dividends. - Keep the divisor fixed. - Compare consecutive quotients for a second constant change.

Solution

1. The dividend increases by \(120\) each step, so the next dividends are \(480\) and \(600\). 2. \(480 \div 6 = 80\) and \(600 \div 6 = 100\). 3. With the divisor fixed at \(6\), increasing the dividend by \(120\) increases the quotient by \(120 \div 6 = 20\).

Answer

\(480 \div 6 = 80\) \(600 \div 6 = 100\) The dividend increases by \(120\), and the quotient increases by \(20\).
Generate shape and number patterns 19
Count forward by \(100\) until you reach the next multiple of \(10{,}000\). a) \(359{,}400, 359{,}500, \ldots, 360{,}000\) b) \(819{,}600, 819{,}700, \ldots, 820{,}000\)

Hints

- Add \(100\) at each step. - Watch what happens when the hundreds digit passes \(9\). - Count how many steps remain before the target.

Solution

1. For a), add \(100\) repeatedly. The missing terms are \(359{,}600\), \(359{,}700\), \(359{,}800\), and \(359{,}900\). 2. For b), the missing terms are \(819{,}800\) and \(819{,}900\).

Answer

a) \(359{,}600, 359{,}700, 359{,}800, 359{,}900\) b) \(819{,}800, 819{,}900\)
Generate shape and number patterns 20
Count forward by ones. What three numbers come after \(399{,}999\)? \(399{,}997, 399{,}998, 399{,}999, \ldots\)

Hints

- Pay close attention to the transition after a number ending in several nines. - Determine how many place values change when \(1\) is added to \(399{,}999\).

Solution

1. \(399{,}999 + 1 = 400{,}000\). 2. \(400{,}000 + 1 = 400{,}001\). 3. \(400{,}001 + 1 = 400{,}002\).

Answer

\(400{,}000, 400{,}001, 400{,}002\)
Generate shape and number patterns 21
Multiply \(505\) by \(3\), \(5\), \(7\), and \(9\). 1. Calculate the four products. 2. Describe the digit pattern in the products.

Hints

- Calculate all four products carefully. - Compare the first two digits with the last two digits in each product. - Relate the repeated block to the multiplication facts for \(5\).

Solution

1. The products are \(505\times 3=1515\), \(505\times 5=2525\), \(505\times 7=3535\), and \(505\times 9=4545\). 2. Each product consists of the same two-digit block repeated twice. 3. That two-digit block equals \(5\) times the one-digit factor: \(5\times 3=15\), \(5\times 5=25\), \(5\times 7=35\), and \(5\times 9=45\).

Answer

1. \(1515,2525,3535,4545\) 2. Each product repeats the same two-digit block twice. The block is \(5\) times the factor.
Generate shape and number patterns 22
Multiply \(198\) by \(2\), \(3\), \(4\), and \(5\). a) Calculate the four products. b) What do you notice about the tens digit of every product? c) Add the hundreds digit and ones digit of each product. What do you notice?

Hints

- Calculate each product carefully. - Compare the middle digit of the four products. - Add the first and last digit of each product.

Solution

1. The products are \(198\times 2=396\), \(198\times 3=594\), \(198\times 4=792\), and \(198\times 5=990\). 2. The tens digit is \(9\) in every product. 3. The outer digits also add to \(9\): \(3+6=9\), \(5+4=9\), \(7+2=9\), and \(9+0=9\).

Answer

a) \(396,594,792,990\) b) The tens digit is always \(9\). c) The hundreds digit and ones digit always add to \(9\).
Generate shape and number patterns 23
Continue the sequence using this rule: each new term is the sum of the two previous terms. Write the sequence through the sixth term. Starting terms: \(2400\) and \(3700\)

Hints

- Add the two most recent terms to find the next term. - Begin by adding the two starting terms. - After each step, use the new term as one of the next two addends.

Solution

1. The third term is \(2400 + 3700 = 6100\). 2. The fourth term is \(3700 + 6100 = 9800\). 3. The fifth term is \(6100 + 9800 = 15{,}900\). 4. The sixth term is \(9800 + 15{,}900 = 25{,}700\).

Answer

\(2400, 3700, 6100, 9800, 15{,}900, 25{,}700\)
Generate shape and number patterns 24
The terms shown are \(92, 84, 76, 68, 60, \ldots\). Find a simple repeating rule that fits these terms. Use your rule to write the next five terms.

Hints

- Compare neighboring terms and record their changes. - Look for a simple change that repeats across all the shown terms. - State the rule you choose before extending the pattern.

Solution

1. The difference between each neighboring pair shown is \(8\). 2. A simple rule that fits is “subtract \(8\) each time.” 3. Applying that rule gives \(52,44,36,28,20\).

Answer

One simple rule that fits is to subtract \(8\) each time. The next five terms are \(52, 44, 36, 28, 20\).
Generate shape and number patterns 25
A number pattern starts with \(2\) and \(3\). Each new term is the sum of the two terms immediately before it. Find the first ten terms.

Hints

- Write the first two terms. - Add them to find the third term. - Keep using the two most recent terms until you have ten terms.

Solution

1. Start with \(2, 3\). 2. Add the two preceding terms each time: \(2+3=5\), \(3+5=8\), \(5+8=13\), \(8+13=21\), \(13+21=34\), \(21+34=55\), \(34+55=89\), and \(55+89=144\).

Answer

\(2; 3; 5; 8; 13; 21; 34; 55; 89; 144\)
Generate shape and number patterns 26
A number pattern starts with \(10\). To find each new term, double the previous term and then subtract \(5\). Write the first six terms.

Hints

- “Double” means multiply by \(2\). - Subtract \(5\) after doubling. - Use each new term to create the next term.

Solution

1. Start with \(10\). 2. Apply the rule repeatedly: \(10\times2-5=15\), \(15\times2-5=25\), \(25\times2-5=45\), \(45\times2-5=85\), and \(85\times2-5=165\).

Answer

\(10, 15, 25, 45, 85, 165\)
Generate shape and number patterns 27
For each row, use a simple constant-step rule that fits all three shown terms, then write the next three terms. a) \(60{,}200, 60{,}100, 60{,}000, \ldots\) b) \(899{,}997, 899{,}998, 899{,}999, \ldots\) c) \(120{,}000, 110{,}000, 100{,}000, \ldots\)

Hints

- Find the difference between the first two terms in each pattern. - Decide whether each pattern increases or decreases. - Watch for changes across a major place-value boundary.

Solution

1. For a), subtract \(100\) each time. The next terms are \(59{,}900\), \(59{,}800\), and \(59{,}700\). 2. For b), add \(1\) each time. The next terms are \(900{,}000\), \(900{,}001\), and \(900{,}002\). 3. For c), subtract \(10{,}000\) each time. The next terms are \(90{,}000\), \(80{,}000\), and \(70{,}000\).

Answer

a) \(59{,}900, 59{,}800, 59{,}700\) b) \(900{,}000, 900{,}001, 900{,}002\) c) \(90{,}000, 80{,}000, 70{,}000\)
Generate shape and number patterns 28
Write the five numbers that come immediately before \(300{,}003\) in the counting sequence.

Hints

- Count backward by ones. - Pay attention when subtracting \(1\) from a number ending in zeros. - Present the five numbers in their normal increasing order.

Solution

1. Count backward by \(1\): \(300{,}002\), \(300{,}001\), \(300{,}000\), \(299{,}999\), and \(299{,}998\). 2. Write those five numbers in increasing order: \(299{,}998, 299{,}999, 300{,}000, 300{,}001, 300{,}002\).

Answer

\(299{,}998, 299{,}999, 300{,}000, 300{,}001, 300{,}002\)
Generate shape and number patterns 29
Count forward by tens. What four numbers come immediately after \(699{,}980\)?

Hints

- Add \(10\) at each step. - Track the tens digit. - Pay attention to the transition after \(699{,}990\).

Solution

1. \(699{,}980 + 10 = 699{,}990\). 2. \(699{,}990 + 10 = 700{,}000\). 3. Continue by tens: \(700{,}010\) and \(700{,}020\).

Answer

\(699{,}990, 700{,}000, 700{,}010, 700{,}020\)
Generate shape and number patterns 30
Continue the number pattern. The first two terms are \(999{,}800\) and \(999{,}850\). Each term increases by the same amount. Write the next three terms.

Hints

- Find how much the pattern increases from the first term to the second. - Add that same amount for each new term. - Pay attention to the place-value change after \(999{,}950\).

Solution

1. Find the difference between the first two terms: \(999{,}850 - 999{,}800 = 50\). 2. Add \(50\) repeatedly: \(999{,}850 + 50 = 999{,}900\), \(999{,}900 + 50 = 999{,}950\), and \(999{,}950 + 50 = 1{,}000{,}000\).

Answer

\(999{,}900, 999{,}950, 1{,}000{,}000\)
Generate shape and number patterns 31
Start at \(8970\) and list the next five numbers in each pattern. a) Count forward by tens. b) Count backward by hundreds. c) Count forward by fives.

Hints

- Decide whether each pattern increases or decreases. - Change the correct place value at every step. - Pay attention when the pattern crosses a multiple of \(1000\).

Solution

1. a) Add \(10\) five times: \(8980, 8990, 9000, 9010, 9020\). 2. b) Subtract \(100\) five times: \(8870, 8770, 8670, 8570, 8470\). 3. c) Add \(5\) five times: \(8975, 8980, 8985, 8990, 8995\).

Answer

a) \(8980, 8990, 9000, 9010, 9020\) b) \(8870, 8770, 8670, 8570, 8470\) c) \(8975, 8980, 8985, 8990, 8995\)
Generate shape and number patterns 32
Panels a), b), and c) show three rectangular dot arrays. Describe a rule relating the number of rows to the total number of dots. If the same rule is used for an array with \(9\) rows, how many dots will it contain?
Figure for problem 537389

Hints

- Count rows and total dots in more than one panel. - Look for a quantity that stays the same in every row. - Use the relationship you identify, not just the next displayed panel.

Solution

1. The panels show \(2\) rows and \(14\) dots, \(4\) rows and \(28\) dots, and \(6\) rows and \(42\) dots. 2. Each row contains \(7\) dots, so the rule is to multiply the number of rows by \(7\). 3. For \(9\) rows, \(9\times7=63\) dots.

Answer

Rule: multiply the number of rows by \(7\). An array with \(9\) rows contains \(63\) dots.
Generate shape and number patterns 33
The same triangular shape is shown in three successive stages. Describe the turn from one stage to the next. Which direction will the triangle point in Stage \(4\)?
Figure for problem 554396

Hints

- Focus on the direction of the triangle's point, not its size. - Compare the turn from Stage \(1\) to Stage \(2\) with the turn from Stage \(2\) to Stage \(3\). - Apply the same turn once more.

Solution

1. The triangle points right, then up, then left. 2. Each stage is a quarter-turn counterclockwise from the previous stage. 3. Another quarter-turn makes the triangle point down in Stage \(4\).

Answer

The rule is a quarter-turn counterclockwise each stage. In Stage \(4\), the triangle points down.
Generate shape and number patterns 34
The three panels show a growing square pattern on a unit grid. Each grid interval represents \(1\) unit. Describe how the side length changes. What will the side length and perimeter be in Stage \(4\)?
Figure for problem 554397

Hints

- Count grid intervals along one side in each stage. - State the change in side length before predicting the next stage. - Use the predicted side length to determine the perimeter.

Solution

1. The side lengths are \(1\), \(2\), and \(3\) units. 2. The side length increases by \(1\) unit each stage, so Stage \(4\) has side length \(4\) units. 3. A square with side length \(4\) units has perimeter \(4\times4=16\) units.

Answer

The side lengths are \(1,2,3\) units, so the side length increases by \(1\) unit at each stage. Stage \(4\) therefore has side length \(4\) units and perimeter \(16\) units.
Generate shape and number patterns 35
These are Stages \(1\) and \(2\) of a shape pattern. The same change is repeated at each step. a) What changes from Stage \(1\) to Stage \(2\)? Describe what happens to the point and the short slanted edge near the bottom. b) If you repeat that change, which way will the point face in Stage \(3\), and where will the short lower edge be?
Figure for problem 554403

Hints

- Compare the pointed ends first. - Does the short edge stay near the bottom in both pictures? - Apply the same change once more to both features.

Solution

1. The point switches from right to left, and the short lower edge switches from the lower left to the lower right. The shape flips left to right without turning upside down. 2. Repeating this flip gives Stage \(3\) a point facing right and the short edge on the lower left.

Answer

a) The point switches right to left, and the short lower edge switches from the left to the right. b) Stage \(3\): point faces right; short edge is on the lower left.
Generate shape and number patterns 36
Complete this addition wall. Each brick equals the sum of the two bricks directly beneath it. What is the top number?
Figure for problem 558891

Hints

- Trace which two bottom bricks support each empty middle brick. - Which empty bricks can you work out before you try the top one?

Solution

1. The middle-left brick is \(2 + 4 = 6\). 2. The middle-right brick is \(4 + 6 = 10\). 3. The top brick is \(6 + 10 = 16\).

Answer

Middle bricks: \(6\) and \(10\). Top brick: \(16\).
Generate shape and number patterns 37
In this addition wall, each brick equals the sum of the two bricks directly below it. Find the missing bottom number and the top number.
Figure for problem 558898

Hints

- Use the middle-left brick to work backward to the bottom row. - Fill the right middle brick using its two bottom neighbors. - Only then find the top.

Solution

1. The lower-left brick is \(7 - 3 = 4\), since the middle-left brick is \(7\). 2. The middle-right brick is \(3 + 5 = 8\). 3. The top brick is \(7 + 8 = 15\).

Answer

Missing bottom number: \(4\). Top number: \(15\).
Generate shape and number patterns 38
The rule has two steps: multiply by a whole number, then add a whole number. Use the same two numbers each time. <table><tr><th>Input</th><th>Output</th></tr><tr><td>1</td><td>4</td></tr><tr><td>2</td><td>7</td></tr><tr><td>3</td><td>10</td></tr><tr><td>5</td><td>\(\square\)</td></tr></table> Find the two numbers in the rule and the missing output.

Hints

- Look at how the output changes when the input goes up by one. - Check a possible rule against all three completed rows.

Solution

1. Each output is three times the input plus one: \(3 \times 1 + 1 = 4\), \(3 \times 2 + 1 = 7\), and \(3 \times 3 + 1 = 10\). 2. For input \(5\), calculate \(3 \times 5 + 1 = 16\).

Answer

\(16\); multiply the input by \(3\) and add \(1\).
Generate shape and number patterns 39
Maya writes the pattern \(3,6,12,24\). She says the next number is \(27\). Is she right? Explain the rule and correct her prediction if needed.

Hints

- Look at both the differences and the products between neighboring terms. - Does the same change work at every step?

Solution

1. Each number is twice the previous one: \(3 \times 2 = 6\), \(6 \times 2 = 12\), and \(12 \times 2 = 24\). 2. The next number is \(24 \times 2 = 48\), not \(27\).

Answer

No. The rule is double each time, so the next number is \(48\).
Generate shape and number patterns 40
Both addition walls follow the rule that the top brick is the sum of the bottom bricks. How much larger is the top brick in b) than in a)? Explain which change in the bottom row causes this.
Figure for problem 558915

Hints

- Compare the two bottom rows first. - Find each top number using the same wall rule. - Notice what changes and what stays the same.

Solution

1. Wall a) has top \(2 + 5 = 7\). 2. Wall b) has top \(3 + 5 = 8\). 3. One bottom brick grew by \(1\) while the other stayed the same, so the top grew by \(8 - 7 = 1\).

Answer

\(1\) larger; the left bottom brick increased by \(1\).
Generate shape and number patterns 41
Noor makes a straight row of touching squares from sticks. Each new square shares one side with the square before it. She has \(19\) sticks. Can she use every stick to make a row of complete squares? If so, how many squares?

Hints

- Start by working out the sticks needed for one square. - Draw a second square sharing a side and see how the total changes. - Continue until you reach or pass the number of sticks Noor has.

Solution

1. The first square needs \(4\) sticks. Every later square needs \(3\) more because it shares a side. 2. The stick totals for \(1\) through \(6\) squares are \(4, 7, 10, 13, 16, 19\). 3. Noor can use all \(19\) sticks to make \(6\) squares.

Answer

Yes; \(6\) touching squares.
Generate shape and number patterns 42
The pattern is \(3,6,8,16,18,\dots\). What are the next two numbers? Explain how the pattern changes from one number to the next.

Hints

- Compare the first pair of numbers, then the next pair. Do they change in the same way? - Look for a short sequence of steps that works more than once.

Solution

1. After \(18\), the next operation is multiply by \(2\), giving \(18 \times 2 = 36\). 2. Then add \(2\), giving \(36 + 2 = 38\).

Answer

\(36,38\). Multiply by \(2\) after \(18\), then add \(2\) after \(36\); those two steps repeat in that order.
Generate shape and number patterns 43
Two patterns start at \(2\). Pattern A adds \(2\) each time. Pattern B doubles each time. Find the number after two steps in each pattern. Why do the results differ even though both patterns start the same?

Hints

- Apply each rule to the same starting number. - Do not assume two patterns are identical just because one term matches. - Follow each rule a second time and compare.

Solution

1. Pattern A is \(2,4,6\) after two steps. 2. Pattern B is \(2,4,8\) after two steps. 3. The first step happens to give the same result, but adding two and doubling make different changes afterward.

Answer

A ends at \(6\); B ends at \(8\). Adding \(2\) always increases the number by \(2\), but doubling changes by an amount that depends on the current number. Both reach \(4\) first; then they split.
Generate shape and number patterns 44
Wall a) is an addition wall: the top is the sum of the two bottom bricks. Wall b) is a product wall: the top is their product. Find both top numbers and explain why they differ.
Figure for problem 558929

Hints

- Before calculating, guess which wall will have the larger top number. - Once you have both results, ask what was different about the two walls.

Solution

1. In a), the top is \(2 + 4 = 6\). 2. In b), the top is \(2 \times 4 = 8\). 3. The bottom numbers are the same, but the two walls use different operations.

Answer

a) \(6\), because \(2 + 4 = 6\). b) \(8\), because \(2 \times 4 = 8\). The bottom numbers match, but one wall adds them and the other multiplies them.
Generate shape and number patterns 45
Using a simple regular rule that fits all the shown terms, continue the sequence and explain that rule. \(320, 321, 323, 326, 330, \ldots, \ldots, \ldots, 356\)

Hints

- Find how much is added from one term to the next. - Compare the successive differences. - Determine how the differences themselves change.

Solution

1. The changes are \(321-320=1\), \(323-321=2\), \(326-323=3\), and \(330-326=4\). 2. The amount added increases by \(1\) each time. 3. Continue by adding \(5\), \(6\), and \(7\): \(330+5=335\), \(335+6=341\), and \(341+7=348\). 4. Adding \(8\) gives \(348+8=356\), which matches the final term.

Answer

The missing numbers are \(335, 341,\) and \(348\). One simple rule that fits: add \(1, 2, 3, 4, 5, \ldots\), increasing the amount added by \(1\) each time.
Generate shape and number patterns 46
Find a simple repeating rule that fits all the shown terms, then use that rule to fill in the missing terms. \(650, 660, 655, 665, 660, \ldots, \ldots, 675\)

Hints

- Compare two consecutive changes rather than only one. - Consider whether two different operations alternate. - Test an “add, then subtract” pattern.

Solution

1. The first changes are \(+10\), then \(-5\). 2. The same pair of changes repeats: \(655+10=665\) and \(665-5=660\). 3. Continue the alternating pattern: \(660+10=670\), then \(670-5=665\). 4. The next \(+10\) step gives \(665+10=675\), which matches the final term.

Answer

The missing numbers are \(670\) and \(665\). One simple rule that fits: alternate between adding \(10\) and subtracting \(5\).
Generate shape and number patterns 47
Study this pattern of addition equations: \(245{,}100 + 312{,}400 = 557{,}500\) \(255{,}200 + 322{,}500 = 577{,}700\) \(265{,}300 + 332{,}600 = 597{,}900\) a) Continue the pattern by writing the fourth equation. b) By how much does the sum increase from one equation to the next? Explain using the addends.

Hints

- Find how the first addend changes from one row to the next. - Find how the second addend changes. - Combine the two changes to determine the change in the sum.

Solution

1. Each addend increases by \(10{,}100\). The next addends are \(265{,}300 + 10{,}100 = 275{,}400\) and \(332{,}600 + 10{,}100 = 342{,}700\). 2. The fourth equation is \(275{,}400 + 342{,}700 = 618{,}100\). 3. Because both addends increase by \(10{,}100\), the sum increases by \(10{,}100 + 10{,}100 = 20{,}200\) each time.

Answer

a) \(275{,}400 + 342{,}700 = 618{,}100\) b) The sum increases by \(20{,}200\) because each addend increases by \(10{,}100\).
Generate shape and number patterns 48
One equation does not follow the pattern. 1) \(980{,}000 - 450{,}000 = 530{,}000\) 2) \(950{,}000 - 420{,}000 = 530{,}000\) 3) \(920{,}000 - 390{,}000 = 530{,}000\) 4) \(890{,}000 - 350{,}000 = 540{,}000\) a) Which equation breaks the pattern? b) Correct the fourth equation so that it follows the pattern.

Hints

- Compare the differences in the first three equations. - Track how both numbers in each subtraction change. - If both numbers decrease by the same amount, the difference stays the same.

Solution

1. In the first three equations, both the minuend and subtrahend decrease by \(30{,}000\), so the difference remains \(530{,}000\). 2. The fourth minuend correctly decreases to \(890{,}000\), but the subtrahend should decrease from \(390{,}000\) to \(360{,}000\). 3. The corrected equation is \(890{,}000 - 360{,}000 = 530{,}000\).

Answer

a) Equation 4 b) \(890{,}000 - 360{,}000 = 530{,}000\)
Generate shape and number patterns 49
Build an addition pattern using these rules: - The first equation is \(300{,}000 + 200{,}000 = 500{,}000\). - In each new equation, the first addend increases by \(50{,}000\). - In each new equation, the second addend decreases by \(20{,}000\). Find the fifth equation and its sum.

Hints

- You may write the second, third, and fourth equations before finding the fifth. - The change is applied four times after the first equation. - Each step changes the total by the increase in one addend minus the decrease in the other.

Solution

1. From the first equation to the fifth, each change happens \(4\) times. 2. The first addend becomes \(300{,}000 + 4 \times 50{,}000 = 500{,}000\). 3. The second addend becomes \(200{,}000 - 4 \times 20{,}000 = 120{,}000\). 4. The fifth equation is \(500{,}000 + 120{,}000 = 620{,}000\).

Answer

\(500{,}000 + 120{,}000 = 620{,}000\)
Generate shape and number patterns 50
Choose two consecutive digits from \(1\) through \(9\), such as \(3\) and \(4\). a) Use the digits to form the two four-digit numbers with patterns \(abba\) and \(baab\). For \(3\) and \(4\), the numbers are \(3443\) and \(4334\). b) Subtract the smaller number from the larger number. c) Repeat with a different pair of consecutive digits. What pattern do you notice?

Hints

- Consecutive digits differ by \(1\). - Check each subtraction carefully. - Compare the results from parts b and c.

Solution

1. With \(3\) and \(4\), the numbers are \(3443\) and \(4334\), and \(4334-3443=891\). 2. With \(7\) and \(8\), the numbers are \(7887\) and \(8778\), and \(8778-7887=891\). 3. The difference is always \(891\) when the two selected digits differ by \(1\).

Answer

a) Example: The digits \(3\) and \(4\) form \(3443\) and \(4334\). b) \(4334 - 3443 = 891\) c) Example: The digits \(7\) and \(8\) give \(8778 - 7887 = 891\). The difference is always \(891\).
Generate shape and number patterns 51
Investigate three-digit numbers and their reversed numbers. a) Choose a three-digit number that does not end in \(0\) and whose hundreds digit is exactly \(3\) greater than its ones digit. One example is \(653\). b) Reverse the digits and subtract the reversed number from your chosen number. c) Repeat with two other numbers that meet the same condition. What do you notice?

Hints

- The tens digit may be any digit. - Reverse the digit order exactly. - Subtract one place at a time and compare your results.

Solution

1. For \(653\), the reversed number is \(356\), and \(653-356=297\). 2. For \(411\), the reversed number is \(114\), and \(411-114=297\). 3. For \(906\), the reversed number is \(609\), and \(906-609=297\). 4. The difference is always \(297\) when the hundreds digit is \(3\) greater than the ones digit.

Answer

a) Example: \(653\) meets the condition. b) Reversing the digits gives \(356\), and \(653 - 356 = 297\). c) For example, \(411 - 114 = 297\) and \(906 - 609 = 297\). The difference is always \(297\).
Generate shape and number patterns 52
Use a simple regular rule for the two factors that fits the first four rows. One equation breaks that rule. Which equation is it? 1. \(10\times 100=1000\) 2. \(20\times 90=1800\) 3. \(30\times 80=2400\) 4. \(40\times 70=2800\) 5. \(50\times 50=2500\)

Hints

- Track how the first factor changes from one equation to the next. - Then track how the second factor changes. - Check whether the last equation follows both rules.

Solution

1. The first factors are \(10,20,30,40,50\), increasing by \(10\). 2. The second factors should be \(100,90,80,70,60\), decreasing by \(10\). 3. Therefore, the fifth equation should use \(60\), not \(50\). 4. The corrected equation is \(50\times 60=3000\). The products then increase by \(800,600,400,200\).

Answer

Equation 5 breaks the pattern. It should be \(50\times 60=3000\).
Generate shape and number patterns 53
Using a simple regular rule that fits the shown factor changes, continue the multiplication pattern with three more equations and describe what happens to the products. \(10\times 90=\square\) \(20\times 80=\square\) \(30\times 70=\square\) \(40\times 60=\square\)

Hints

- Track both factors at the same time. - Calculate the products for the continued equations. - Compare later products with earlier products for symmetry. - Notice how the differences between consecutive products change.

Solution

1. The given products are \(900,1600,2100,2400\). 2. The first factor increases by \(10\), and the second factor decreases by \(10\). 3. The next equations are \(50\times 50=2500\), \(60\times 40=2400\), and \(70\times 30=2100\). 4. The products increase to a maximum of \(2500\) and then decrease. The products repeat in reverse order around \(50\times 50\).

Answer

\(50\times 50=2500\) \(60\times 40=2400\) \(70\times 30=2100\) The products rise to \(2500\) and then fall, repeating earlier values in reverse order.
Generate shape and number patterns 54
Calculate the quotients in this pattern. Then write the next two division equations and their answers. Explain how the divisors and quotients change. \(900\div9\) \(720\div8\) \(560\div7\) \(420\div6\) \(300\div5\)

Hints

- Calculate the equations you already have before predicting more. - Check whether the divisor and quotient change in the same way. - Use multiplication to test your next two equations.

Solution

1. The divisors go down by \(1\): \(9,8,7,6,5\). The next two are \(4\) and \(3\). 2. The quotients are \(100,90,80,70,60\), going down by \(10\). The next two are \(50\) and \(40\). 3. The next dividends are \(4\times50=200\) and \(3\times40=120\). 4. The next equations are \(200\div4=50\) and \(120\div3=40\).

Answer

\(200\div4=50\) \(120\div3=40\)
Generate shape and number patterns 55
Follow the pattern and write the next division equation. \(45\div8=5\,\text{R}\,5\) \(36\div8=4\,\text{R}\,4\) \(27\div8=3\,\text{R}\,3\) \(18\div8=2\,\text{R}\,2\) \(9\div8=1\,\text{R}\,1\)

Hints

- Watch how each dividend changes from one line to the next. - Which parts of the quotient-and-remainder results are changing? - Does zero need a written remainder?

Solution

1. The dividends decrease by \(9\) each time, so the next dividend is \(9-9=0\). 2. The divisor stays \(8\); both quotient and remainder have been decreasing by \(1\). 3. Zero divided by eight is exact, so the next equation is \(0\div8=0\).

Answer

\(0\div8=0\)
Generate shape and number patterns 56
Give a simple regular rule that fits all the shown division equations, then use it to write the next two equations. \(20\div2=10\) \(33\div3=11\) \(48\div4=12\) \(65\div5=13\) \(84\div6=14\)

Hints

- Examine how the divisors change from row to row. - Examine how the quotients change from row to row. - Once those two values are known for a new row, determine the dividend that makes the equation true.

Solution

1. The divisors increase by \(1\), so the next divisors are \(7\) and \(8\). 2. The quotients increase by \(1\), so the next quotients are \(15\) and \(16\). 3. The matching dividends are \(15\times7=105\) and \(16\times8=128\). 4. The next equations are \(105\div7=15\) and \(128\div8=16\).

Answer

A simple rule that fits is: increase the divisor by \(1\), increase the quotient by \(1\), and use their product as the dividend. The next equations are \(105\div7=15\) \(128\div8=16\).
Generate shape and number patterns 57
Determine which division expressions have the same quotient. Make a prediction from the relationships among the numbers, explain it, and then verify each quotient. a) \(744\div 6\) b) \(372\div 3\) c) \(744\div 3\) d) \(248\div 2\)

Hints

- Compare \(744\) with \(372\) and \(6\) with \(3\). - Look for a similar relationship between parts a and d. - Verify the predicted quotients with division.

Solution

1. In part b, both the dividend and divisor from part a are halved, so the quotient remains the same. 2. In part d, both the dividend and divisor from part a are divided by \(3\), so the quotient again remains the same. 3. Verify: \(744\div 6=124\), \(372\div 3=124\), \(744\div 3=248\), and \(248\div 2=124\). 4. Therefore, parts a, b, and d have the same quotient.

Answer

a), b), and d) have the same quotient, \(124\). Part c equals \(248\).
Generate shape and number patterns 58
Calculate and compare the quotients. How are the changes in the dividends related to each divisor? a) \(560\div 7\), \(567\div 7\), \(553\div 7\) b) \(420\div 6\), \(426\div 6\), \(414\div 6\) c) \(320\div 4\), \(328\div 4\), \(312\div 4\)

Hints

- Calculate the first quotient in each row. - Compare the dividends within a row. - Express each dividend difference as a multiple of the divisor. - Use that relationship to predict the other quotients.

Solution

1. Part a gives \(80,81,79\). Adding or subtracting one divisor changes the quotient by \(1\). 2. Part b gives \(70,71,69\). Again, adding or subtracting one divisor changes the quotient by \(1\). 3. Part c gives \(80,82,78\). Adding or subtracting \(8\), which is twice the divisor, changes the quotient by \(2\). 4. In general, changing the dividend by a multiple of the divisor changes the quotient by that same multiple.

Answer

a) \(80,81,79\) b) \(70,71,69\) c) \(80,82,78\) Changing the dividend by a multiple of the divisor changes the quotient by the same multiple.
Generate shape and number patterns 59
Calculate each group. What do you notice about the quotients? a) \(640\div 8\), \(320\div 4\), \(160\div 2\) b) \(420\div 6\), \(210\div 3\), \(70\div 1\) c) \(240\div 6\), \(120\div 3\), \(40\div 1\)

Hints

- Compare how the dividend and divisor change from one expression to the next. - Calculate the first quotient in each group. - Predict the other quotients before calculating. - State a rule that explains why the quotient stays the same.

Solution

1. Part a gives \(80,80,80\). 2. Part b gives \(70,70,70\). 3. Part c gives \(40,40,40\). 4. Within each group, the dividend and divisor are divided by the same number. This keeps the quotient unchanged.

Answer

a) \(80,80,80\) b) \(70,70,70\) c) \(40,40,40\) Dividing the dividend and divisor by the same nonzero number does not change the quotient.
Generate shape and number patterns 60
Write the next division equation and explain why its quotient will match the others. \(64{,}000\div8=8000\) \(56{,}000\div7=8000\) \(48{,}000\div6=8000\) \(40{,}000\div5=8000\)

Hints

- Compare the changes on the left side of the equations. - Look at what happens to the answers as the divisor gets smaller. - Multiply the numbers in your final equation to check it.

Solution

1. The quotient stays \(8000\) while the divisor decreases by \(1\). 2. The dividend drops by \(8000\), so the next is \(40{,}000-8000=32{,}000\). 3. The next divisor is \(4\), giving \(32{,}000\div4=8000\).

Answer

\(32{,}000\div4=8000\).
Generate shape and number patterns 61
Write the next division equation. Explain how you found all three numbers in it. \(21{,}000\div3=7000\) \(32{,}000\div4=8000\) \(45{,}000\div5=9000\) \(60{,}000\div6=10{,}000\)

Hints

- Compare the divisors and quotients separately. - You may find it easier to predict two numbers before the third. - Check the new equation by multiplication.

Solution

1. The divisors increase by \(1\), so the next is \(7\). 2. The quotients increase by \(1000\), so the next is \(11{,}000\). 3. Find the dividend from their product: \(7\times11{,}000=77{,}000\). 4. The next equation is \(77{,}000\div7=11{,}000\).

Answer

\(77{,}000\div7=11{,}000\).
Generate shape and number patterns 62
Give a simple repeating rule that fits all the shown terms, then use that rule to continue the number pattern with three more numbers. \(850{,}000, 800{,}000, 825{,}000, 775{,}000, 800{,}000, \ldots\)

Hints

- The direction changes from one step to the next. - Examine the first two changes separately. - Look for a repeating two-step rule.

Solution

1. The first change is \(-50{,}000\), and the second change is \(+25{,}000\). 2. These two changes repeat: \(825{,}000 - 50{,}000 = 775{,}000\) and \(775{,}000 + 25{,}000 = 800{,}000\). 3. Continue with \(-50{,}000\): \(800{,}000 - 50{,}000 = 750{,}000\). 4. Then add \(25{,}000\): \(750{,}000 + 25{,}000 = 775{,}000\). 5. Then subtract \(50{,}000\): \(775{,}000 - 50{,}000 = 725{,}000\).

Answer

Next numbers: \(750{,}000, 775{,}000, 725{,}000\) One simple rule that fits: Alternate subtracting \(50{,}000\) and adding \(25{,}000\).
Generate shape and number patterns 63
For each row, give a simple regular rule that fits all the shown terms, then use it to complete the number pattern. a) \(200{,}000, 350{,}000, 500{,}000, \square, \square, 950{,}000\) b) \(900{,}000, 820{,}000, 740{,}000, \square, \square, \square, 420{,}000\) c) \(125{,}000, 250{,}000, 500{,}000, \square\)

Hints

- Ignore the zeros at first and compare the leading values. - Find the difference between consecutive terms in a) and b). - In c), compare each term with the one before it.

Solution

1. For a), add \(150{,}000\) each time. The missing terms are \(650{,}000\) and \(800{,}000\), followed by the given term \(950{,}000\). 2. For b), subtract \(80{,}000\) each time. The missing terms are \(660{,}000\), \(580{,}000\), and \(500{,}000\), followed by the given term \(420{,}000\). 3. For c), multiply by \(2\) each time, so the missing term is \(1{,}000{,}000\).

Answer

a) One simple rule that fits: add \(150{,}000\); missing terms: \(650{,}000, 800{,}000\) b) One simple rule that fits: subtract \(80{,}000\); missing terms: \(660{,}000, 580{,}000, 500{,}000\) c) One simple rule that fits: multiply by \(2\); missing term: \(1{,}000{,}000\)
Generate shape and number patterns 64
Give a simple regular rule that fits all the shown terms, then use it to fill the two blanks. \(100{,}000, 120{,}000, 150{,}000, \square, 240{,}000, 300{,}000, \square\)

Hints

- Find the differences between consecutive known terms. - Examine how the differences themselves change. - Use the pattern of differences on both sides of each blank. - Check that every step follows the same rule.

Solution

1. The first differences are \(20{,}000\) and \(30{,}000\). 2. The amount added increases by \(10{,}000\) each time. 3. Add \(40{,}000\) to \(150{,}000\) to get \(190{,}000\). 4. Then the additions are \(50{,}000\), \(60{,}000\), and \(70{,}000\), so the final missing term is \(300{,}000 + 70{,}000 = 370{,}000\).

Answer

A simple rule that fits is to add \(20{,}000\), then \(30{,}000\), then \(40{,}000\), increasing the amount added by \(10{,}000\) each time. The missing terms are \(190{,}000\) and \(370{,}000\).
Generate shape and number patterns 65
Calculate and continue each sequence with three more expressions. Sequence 1: \(10 \times 20\), \(10 \times 30\), \(10 \times 40\), ... Sequence 2: \(5 \times 20\), \(5 \times 30\), \(5 \times 40\), ... Explain the pattern in the products of Sequence 1.

Hints

- Track the change in the second factor. - Multiplying by \(10\) shifts place value one position. - Compare corresponding products across the two sequences.

Solution

1. Sequence 1 has products \(200\), \(300\), and \(400\), followed by \(10 \times 50 = 500\), \(10 \times 60 = 600\), and \(10 \times 70 = 700\). 2. Sequence 2 has products \(100\), \(150\), and \(200\), followed by \(5 \times 50 = 250\), \(5 \times 60 = 300\), and \(5 \times 70 = 350\). 3. In Sequence 1, the second factor increases by \(10\), so each product increases by \(10 \times 10 = 100\).

Answer

Sequence 1: \(10 \times 50 = 500\), \(10 \times 60 = 600\), \(10 \times 70 = 700\) Sequence 2: \(5 \times 50 = 250\), \(5 \times 60 = 300\), \(5 \times 70 = 350\) Sequence 1 increases by \(100\) each step.
Generate shape and number patterns 66
How many steps of the given size are needed to reach the next thousand? a) Start: \(342{,}400\); step size: \(200\) b) Start: \(712{,}750\); step size: \(50\) c) Start: \(899{,}920\); step size: \(20\)

Hints

- Identify the next thousand after each starting number. - Find how far the starting number is from that target. - Match that distance with repeated equal steps of the stated size.

Solution

1. For a), the next thousand is \(343{,}000\), which is \(600\) away. Since \(200+200+200=600\), it takes \(3\) steps. 2. For b), the next thousand is \(713{,}000\), which is \(250\) away. Five steps of \(50\) make \(250\), so it takes \(5\) steps. 3. For c), the next thousand is \(900{,}000\), which is \(80\) away. Four steps of \(20\) make \(80\), so it takes \(4\) steps.

Answer

a) \(3\) steps b) \(5\) steps c) \(4\) steps
Generate shape and number patterns 67
Complete the table so that each row lands exactly on the target, which is the next thousand. <table><tr><th>Start</th><th>Step size</th><th>Target</th><th>Number of steps</th></tr><tr><td>\(451{,}200\)</td><td>\(200\)</td><td>\(452{,}000\)</td><td>?</td></tr><tr><td>\(123{,}750\)</td><td>?</td><td>\(124{,}000\)</td><td>\(5\)</td></tr><tr><td>?</td><td>\(10\)</td><td>\(888{,}000\)</td><td>\(3\)</td></tr></table>

Hints

- A different value is missing in each row. - Relate the distance from start to target to equal repeated steps. - To find a start, work backward from the target by the stated number of steps.

Solution

1. Row 1: The distance is \(452{,}000-451{,}200=800\). Four steps of \(200\) make \(800\), so the number of steps is \(4\). 2. Row 2: The distance is \(124{,}000-123{,}750=250\). Five equal steps must total \(250\), so each step is \(50\). 3. Row 3: Three steps of \(10\) cover \(3\times10=30\). Counting backward gives \(888{,}000-30=887{,}970\).

Answer

Row 1: \(4\) steps Row 2: step size \(50\) Row 3: start \(887{,}970\)
Generate shape and number patterns 68
In this number pattern, each step adds \(100{,}000 + 10{,}000 + 1000 + 100 + 10 + 1\). a) Continue with two more numbers: \(123{,}456 \to 234{,}567 \to \square \to \square\) b) Find the next number: \(489{,}000 \to 600{,}111 \to \square\) c) How many times must \(111{,}111\) be added to move from \(222{,}222\) to \(888{,}888\)?

Hints

- Combine the place-value amounts to find one complete step. - Add the same amount at every step. - For part c, track repeated additions from the starting number to the target.

Solution

1. The amount added each time is \(111{,}111\). 2. For a), \(234{,}567 + 111{,}111 = 345{,}678\), and \(345{,}678 + 111{,}111 = 456{,}789\). 3. For b), \(600{,}111 + 111{,}111 = 711{,}222\). 4. For c), repeated addition gives \(333{,}333\), \(444{,}444\), \(555{,}555\), \(666{,}666\), \(777{,}777\), and \(888{,}888\), so the amount is added \(6\) times.

Answer

a) \(345{,}678\) and \(456{,}789\) b) \(711{,}222\) c) \(6\) times
Generate shape and number patterns 69
Evaluate each set of division expressions. Then describe the pattern in the quotients. a) \(1{,}000{,}000 \div 1\) \(1{,}000{,}000 \div 10\) \(1{,}000{,}000 \div 100\) \(1{,}000{,}000 \div 1000\) b) \(100{,}000 \div 2\) \(100{,}000 \div 4\) \(100{,}000 \div 8\)

Hints

- In part a, compare the number of zeros in each quotient. - In part b, compare how the divisors change and what happens to the quotients.

Solution

1. For a), the quotients are \(1{,}000{,}000\), \(100{,}000\), \(10{,}000\), and \(1000\). 2. Each divisor in a) is \(10\) times the previous divisor, so each quotient is one-tenth of the previous quotient. 3. For b), the quotients are \(50{,}000\), \(25{,}000\), and \(12{,}500\). 4. Each divisor in b) doubles, so each quotient is half the previous quotient.

Answer

a) \(1{,}000{,}000, 100{,}000, 10{,}000, 1000\); each quotient is one-tenth of the previous quotient. b) \(50{,}000, 25{,}000, 12{,}500\); each quotient is half the previous quotient.
Generate shape and number patterns 70
Find the step size in each pattern and write the next three terms. a) \(0, 150{,}000, 300{,}000, \ldots\) b) \(1{,}000{,}000, 925{,}000, 850{,}000, \ldots\) c) \(500{,}000, 575{,}000, 650{,}000, \ldots\)

Hints

- Find the difference between two consecutive terms. - Decide whether each pattern increases or decreases. - Apply the same step three more times.

Solution

1. For a), the step is \(+150{,}000\). The next terms are \(450{,}000\), \(600{,}000\), and \(750{,}000\). 2. For b), the step is \(-75{,}000\). The next terms are \(775{,}000\), \(700{,}000\), and \(625{,}000\). 3. For c), the step is \(+75{,}000\). The next terms are \(725{,}000\), \(800{,}000\), and \(875{,}000\).

Answer

a) Step: \(+150{,}000\); next terms: \(450{,}000, 600{,}000, 750{,}000\) b) Step: \(-75{,}000\); next terms: \(775{,}000, 700{,}000, 625{,}000\) c) Step: \(+75{,}000\); next terms: \(725{,}000, 800{,}000, 875{,}000\)
Generate shape and number patterns 71
Luke and Maya count within \(1{,}000{,}000\). Luke counts forward by \(250{,}000\), starting at \(0\). Maya counts backward by \(100{,}000\), starting at \(1{,}000{,}000\). Which numbers appear in both counting patterns?

Hints

- Write each counting pattern completely. - Compare the two lists. - Mark every number that appears in both.

Solution

1. Luke's pattern is \(0, 250{,}000, 500{,}000, 750{,}000, 1{,}000{,}000\). 2. Maya's pattern contains every multiple of \(100{,}000\) from \(1{,}000{,}000\) down to \(0\). 3. The numbers in both patterns are \(0\), \(500{,}000\), and \(1{,}000{,}000\).

Answer

\(0\), \(500{,}000\), and \(1{,}000{,}000\)
Generate shape and number patterns 72
Using a simple regular rule that fits the three shown equations, continue the pattern for two more rows and describe the sums. \(12{,}121+21{,}212=33{,}333\) \(23{,}232+21{,}212=44{,}444\) \(34{,}343+21{,}212=55{,}555\)

Hints

- Compare the first addends from one row to the next. - Use the same increase to predict the next first addend and sum. - Look at the digits in each sum. - Describe what all the sums have in common.

Solution

1. The first addend increases by \(11{,}111\) in each row, so the sum increases by \(11{,}111\). 2. The next two rows are \(45{,}454+21{,}212=66{,}666\) and \(56{,}565+21{,}212=77{,}777\). 3. Each sum has the same digit in all five places.

Answer

\(45{,}454+21{,}212=66{,}666\) \(56{,}565+21{,}212=77{,}777\) Every sum has one digit repeated in all five places.
Generate shape and number patterns 73
Using a simple regular rule that fits the three shown equations, write the next equation before calculating it. Then explain why all the shown and predicted sums are equal. \(12{,}345+87{,}654=99{,}999\) \(23{,}456+76{,}543=99{,}999\) \(34{,}567+65{,}432=99{,}999\)

Hints

- Compare the first addends in consecutive rows. - Compare the second addends in consecutive rows. - Check whether the two changes have the same size. - Use those changes to write the next equation.

Solution

1. The first addend increases by \(11{,}111\), while the second addend decreases by \(11{,}111\). 2. The next equation is \(45{,}678+54{,}321=99{,}999\). 3. Because one addend increases by exactly the amount the other decreases, the sum remains unchanged.

Answer

\(45{,}678+54{,}321=99{,}999\) Each time, one addend increases by \(11{,}111\) and the other decreases by \(11{,}111\), so the sum stays \(99{,}999\).
Generate shape and number patterns 74
Using a simple regular rule that fits the four shown equations, continue the pattern for two more rows and describe how the digits change. \(4321-2889=1432\) \(5432-2889=2543\) \(6543-2889=3654\) \(7654-2889=4765\)

Hints

- Compare consecutive minuends and consecutive differences. - Use the common increase to predict the next two rows. - Compare the digit order in each minuend and its difference. - Describe the repeated digit movement.

Solution

1. Each minuend increases by \(1111\), so each difference also increases by \(1111\). 2. The next two rows are \(8765-2889=5876\) and \(9876-2889=6987\). 3. In each row, the last digit of the minuend becomes the first digit of the difference, and the other three digits shift one place to the right.

Answer

\(8765-2889=5876\) \(9876-2889=6987\) The last digit of each minuend moves to the front of the difference, while the other digits shift one place to the right.
Generate shape and number patterns 75
Complete each set of equations. Then describe how the quotients change. a) \(48{,}000\div 2=\square\) \(48{,}000\div 4=\square\) \(48{,}000\div 6=\square\) \(48{,}000\div 8=\square\) b) \(12{,}000\div 3=\square\) \(24{,}000\div 3=\square\) \(36{,}000\div 3=\square\) \(48{,}000\div 3=\square\)

Hints

- Identify which number stays fixed in each part. - Use basic division facts, then account for the zeros. - Compare consecutive dividends, divisors, and quotients. - Describe each pattern separately.

Solution

1. In part a, the dividend stays \(48{,}000\) while the divisor increases. The quotients are \(24{,}000,12{,}000,8000,6000\). 2. In part b, the divisor stays \(3\) while the dividend increases by \(12{,}000\). The quotients are \(4000,8000,12{,}000,16{,}000\). 3. In part a, larger divisors produce smaller quotients. In part b, each increase of \(12{,}000\) in the dividend increases the quotient by \(4000\).

Answer

a) \(24{,}000,12{,}000,8000,6000\) b) \(4000,8000,12{,}000,16{,}000\) In part a, the quotients decrease as the divisors increase. In part b, the quotients increase by \(4000\) each time.
Generate shape and number patterns 76
A number pattern starts at \(10\). Multiply in this repeating order: by \(10\), then by \(5\), then by \(2\). How many multiplication steps are needed to obtain a number greater than \(5000\)?

Hints

- Keep the repeating factor order visible as you work. - The target must be exceeded, not merely reached. - Count each multiplication as one step.

Solution

1. Apply the repeating factors: \(10\times10=100\), \(100\times5=500\), and \(500\times2=1000\). 2. Continue: \(1000\times10=10{,}000\). 3. The first three results are not greater than \(5000\), but the fourth result is. Therefore, \(4\) multiplication steps are needed.

Answer

\(4\) steps
Generate shape and number patterns 77
Using a simple regular rule that fits the shown equations, continue the sequence with one more equation, calculate all the quotients, and describe the pattern. \(1112\div 8\) \(2224\div 8\) \(3336\div 8\) \(\square\)

Hints

- Determine how the dividend changes from one equation to the next. - Use the same change to write the next dividend. - Compare consecutive quotients. - Relate the change in the quotients to \(1112\div 8\).

Solution

1. The first three quotients are \(1112\div 8=139\), \(2224\div 8=278\), and \(3336\div 8=417\). 2. The dividend increases by \(1112\), so the next equation is \(4448\div 8=556\). 3. Because \(1112\div 8=139\), each increase of \(1112\) in the dividend increases the quotient by \(139\).

Answer

The quotients are \(139,278,417\). The next equation is \(4448\div 8=556\). The quotient increases by \(139\) each time.
Generate shape and number patterns 78
Study the three shown equations and use a simple regular rule that fits them. \(1\times9+2=11\) \(12\times9+3=111\) \(123\times9+4=1111\) a) Using that rule, write and evaluate a fourth equation. b) If the same rule is continued for a fifth row, predict the fifth result without carrying out a new multiplication. Explain how the result pattern supports your prediction.

Hints

- Track how the first factor and added number change from row to row. - Compare the number of \(1\)s in successive results. - For part b), use the visible result pattern rather than a multiplication algorithm.

Solution

1. Each new first factor appends the next digit, and the added number increases by \(1\). 2. The fourth equation is \(1234\times9+5\). Since \(1234\times9=11{,}106\), the result is \(11{,}111\). 3. The results have one more digit \(1\) in each new row: \(11\), \(111\), \(1111\), \(11{,}111\). Therefore, the fifth result is \(111{,}111\) by the pattern, without evaluating a five-digit multiplication.

Answer

a) \(1234\times9+5=11{,}111\). b) A simple rule that fits appends the next digit to the first factor, increases the added number by \(1\), and adds one more digit \(1\) to each result. Therefore, the fifth result is \(111{,}111\) without carrying out a new multiplication.
Generate shape and number patterns 79
Study the shown equations. Use a simple regular rule that fits them to answer both parts. \(6 + 6 = 12\) \(66 + 66 = 132\) \(666 + 666 = 1332\) \(6666 + 6666 = 13{,}332\) a) What is the next equation and result under that rule? b) Describe how the result changes when one more digit \(6\) is added to each addend.

Hints

- Calculate the next equation to test your prediction. - Identify which digits appear in every result. - Compare the number of \(6\)s in an addend with the number of \(3\)s in the result.

Solution

1. The next equation is \(66{,}666 + 66{,}666 = 133{,}332\). 2. Every result begins with \(1\), ends with \(2\), and has only \(3\)s between them. 3. Each added \(6\) in the addends creates one additional \(3\) in the middle of the result.

Answer

a) \(66{,}666 + 66{,}666 = 133{,}332\) b) The result begins with \(1\) and ends with \(2\); each additional \(6\) adds another \(3\) between them.
Generate shape and number patterns 80
Continue both number patterns logically, and find every sum. 1. \(210{,}000+320{,}000=\square\) 2. \(220{,}000+330{,}000=\square\) 3. \(230{,}000+340{,}000=\square\) 4. \(\square+\square=\square\) 5. \(\square+\square=\square\)

Hints

- Determine the change in each addend separately. - Apply both rules to create the next pair of addends. - When both addends increase by the same amount, consider how much the sum increases.

Solution

1. Each first addend increases by \(10{,}000\), and each second addend also increases by \(10{,}000\). 2. The first three sums are \(530{,}000\), \(550{,}000\), and \(570{,}000\). 3. Continue both addend patterns to get \(240{,}000\) and \(350{,}000\), whose sum is \(590{,}000\). 4. Continue once more to get \(250{,}000\) and \(360{,}000\), whose sum is \(610{,}000\).

Answer

1. \(530{,}000\) 2. \(550{,}000\) 3. \(570{,}000\) 4. \(240{,}000+350{,}000=590{,}000\) 5. \(250{,}000+360{,}000=610{,}000\)
Generate shape and number patterns 81
Choose two different digits from \(1\) through \(9\), and call them \(a\) and \(b\). a) Form the two four-digit palindromes \(abba\) and \(baab\). For example, the digits \(3\) and \(8\) form \(3883\) and \(8338\). b) Subtract the smaller palindrome from the larger one. c) Repeat the process with two other pairs of digits. d) Find the sum of the digits in each of your three differences. What do you notice?

Hints

- Keep the outside digits equal and the inside digits equal when forming each palindrome. - Align the numbers by place value before subtracting. - Add every digit in each difference. - Test digit pairs with both small and large differences.

Solution

1. Using \(3\) and \(8\), \(8338-3883=4455\), and \(4+4+5+5=18\). 2. Using \(1\) and \(2\), \(2112-1221=891\), and \(8+9+1=18\). 3. Using \(4\) and \(9\), \(9449-4994=4455\), and the sum of the digits is \(18\). 4. For every valid pair, the sum of the digits in the difference is \(18\).

Answer

a) Example: The digits \(3\) and \(8\) form \(3883\) and \(8338\). b) \(8338 - 3883 = 4455\) c) Examples: \(2112 - 1221 = 891\) and \(9449 - 4994 = 4455\). d) The digit sums are \(18\), \(18\), and \(18\). The sum of the digits in each difference is always \(18\).
Generate shape and number patterns 82
Use two different digits to form the four-digit palindromes \(abba\) and \(baab\). a) Find the sums for the digit pairs \((2,5)\) and \((3,4)\). What do you notice? b) Which two different digits from \(1\) through \(9\) make the sum exactly \(8888\)? Find all three pairs.

Hints

- Add corresponding digits in the two palindromes. - Compare the repeated result digit with the two chosen digits. - For part b, list pairs of different positive digits whose sum is \(8\).

Solution

1. For \((2,5)\), \(2552+5225=7777\). 2. For \((3,4)\), \(3443+4334=7777\). 3. In each place, the result digit is the sum of the two chosen digits, provided that sum is less than \(10\). 4. To obtain \(8888\), the two digits must add to \(8\). 5. The three pairs of different positive digits are \((1,7)\), \((2,6)\), and \((3,5)\).

Answer

a) Both sums are \(7777\). Each result has the same digit in all four places. b) The pairs are \((1,7)\), \((2,6)\), and \((3,5)\).
Generate shape and number patterns 83
A researcher multiplied \(606\) by several one-digit numbers and obtained \(1212\), \(1818\), \(2424\), and \(3030\). 1. Which one-digit factor produced each result? 2. Predict \(606\times 7\) using the pattern.

Hints

- Split each result into two equal two-digit blocks. - Relate each block to a multiplication fact for \(6\). - Use the same relationship for a factor of \(7\).

Solution

1. Each result repeats a two-digit block. Dividing the block values \(12,18,24,30\) by \(6\) gives the factors \(2,3,4,5\). 2. For a factor of \(7\), \(6\times 7=42\). 3. Repeating the block \(42\) gives \(4242\), so \(606\times 7=4242\).

Answer

1. The factors are \(2,3,4,5\), respectively. 2. \(606\times 7=4242\).
Generate shape and number patterns 84
Multiply \(495\) by \(2\), \(3\), \(4\), and \(5\). a) Calculate the four products. b) Find the sum of the digits in each product. What do you notice? c) For each four-digit product, add the first and third digits, and then add the second and fourth digits. What do you notice?

Hints

- Add every digit in each product for part b). - For part c), pair digits that are two places apart. - Compare the two pair sums within each four-digit product.

Solution

1. The products are \(495\times 2=990\), \(495\times 3=1485\), \(495\times 4=1980\), and \(495\times 5=2475\). 2. The sums of the digits are \(9+9+0=18\), \(1+4+8+5=18\), \(1+9+8+0=18\), and \(2+4+7+5=18\). 3. In \(1485\), \(1+8=9\) and \(4+5=9\). The same relationship holds for \(1980\) and \(2475\).

Answer

a) \(990,1485,1980,2475\) b) The sum of the digits is always \(18\). c) In each four-digit product, the first and third digits add to \(9\), and the second and fourth digits also add to \(9\).
Generate shape and number patterns 85
A hundreds chart lists the numbers from \(1\) through \(100\) in ten rows. <table><tbody><tr><td>1</td><td>2</td><td>3</td><td>4</td><td>5</td><td>6</td><td>7</td><td>8</td><td>9</td><td>10</td></tr><tr><td>11</td><td>12</td><td>13</td><td>14</td><td>15</td><td>16</td><td>17</td><td>18</td><td>19</td><td>20</td></tr><tr><td>21</td><td>22</td><td>23</td><td>24</td><td>25</td><td>26</td><td>27</td><td>28</td><td>29</td><td>30</td></tr><tr><td>31</td><td>32</td><td>33</td><td>34</td><td>35</td><td>36</td><td>37</td><td>38</td><td>39</td><td>40</td></tr><tr><td>41</td><td>42</td><td>43</td><td>44</td><td>45</td><td>46</td><td>47</td><td>48</td><td>49</td><td>50</td></tr><tr><td>51</td><td>52</td><td>53</td><td>54</td><td>55</td><td>56</td><td>57</td><td>58</td><td>59</td><td>60</td></tr><tr><td>61</td><td>62</td><td>63</td><td>64</td><td>65</td><td>66</td><td>67</td><td>68</td><td>69</td><td>70</td></tr><tr><td>71</td><td>72</td><td>73</td><td>74</td><td>75</td><td>76</td><td>77</td><td>78</td><td>79</td><td>80</td></tr><tr><td>81</td><td>82</td><td>83</td><td>84</td><td>85</td><td>86</td><td>87</td><td>88</td><td>89</td><td>90</td></tr><tr><td>91</td><td>92</td><td>93</td><td>94</td><td>95</td><td>96</td><td>97</td><td>98</td><td>99</td><td>100</td></tr></tbody></table> 1. Find \(1+100\). 2. Find \(2+99\). 3. Find \(3+98\). 4. What pattern do you notice? How many such pairs can be formed from all \(100\) numbers? 5. Use the pattern to find the sum of all the numbers from \(1\) through \(100\).

Hints

- Pair the smallest unused number with the largest unused number. - Compare the sums of the first few pairs. - Divide the total number of entries by \(2\) to count the pairs. - Multiply the number of pairs by the common pair sum.

Solution

1. The first pair has sum \(1+100=101\). 2. The second pair has sum \(2+99=101\). 3. The third pair has sum \(3+98=101\). 4. Every smallest-largest pair has sum \(101\). The \(100\) numbers form \(50\) pairs. 5. Therefore, the total is \(50\times 101=50\times 100+50=5050\).

Answer

1. \(101\) 2. \(101\) 3. \(101\) 4. Every pair sums to \(101\), and there are \(50\) pairs. 5. The total is \(5050\).
Generate shape and number patterns 86
A four-digit repeating-block number has the form \(abab\). Swapping the digits gives \(baba\). a) Use the digits \(3\) and \(7\) to form \(3737\) and \(7373\). Subtract the smaller number from the larger number. b) Use two other digits that also differ by \(4\), such as \(1\) and \(5\). Find the new difference. What do you notice? c) Use the digits \(2\) and \(3\). How many times as large is the result from part a) as this new difference?

Hints

- Keep the digit order \(abab\) or \(baba\) when forming each number. - Compare the difference between the two chosen digits. - Relate \(909\) to \(3636\) using multiplication.

Solution

1. Part a gives \(7373-3737=3636\). 2. Part b gives \(5151-1515=3636\). Equal digit differences produce equal number differences. 3. Part c gives \(3232-2323=909\). 4. Since \(909\times 4=3636\), the result from part a is four times the result from part c.

Answer

a) \(3636\) b) \(3636\); the differences are equal. c) The new difference is \(909\), and \(3636\) is \(4\) times as large.
Generate shape and number patterns 87
Investigate sums of four-digit repeating-block numbers of the forms \(abab\) and \(baba\). a) Use \(a=2\) and \(b=5\). Find \(2525+5252\). b) Use \(a=1\) and \(b=8\). Find \(1818+8181\). c) Yasmine claims, “If \(a+b=10\), then \(abab+baba\) is always \(11{,}110\).” Test the claim using the digit pairs \((3,7)\) and \((4,6)\).

Hints

- Align the numbers by place value. - Compare the repeated result digit with \(a+b\). - Watch for regrouping when \(a+b=10\). - Test both required digit pairs before deciding about the claim.

Solution

1. Part a gives \(2525+5252=7777\). 2. Part b gives \(1818+8181=9999\). 3. For \((3,7)\), \(3737+7373=11{,}110\). 4. For \((4,6)\), \(4646+6464=11{,}110\). 5. Both required tests give \(11{,}110\), so they support Yasmine's claim for the specified test cases.

Answer

a) \(7777\) b) \(9999\) c) The claim is supported: \(3737+7373=11{,}110\) and \(4646+6464=11{,}110\).
Generate shape and number patterns 88
Find the sum of all four-digit palindromes that begin and end with \(1\): \(1001,1111,1221,1331,1441,1551,1661,1771,1881,1991\)

Hints

- Pair the first number with the last number. - Continue pairing numbers from the outside inward. - Check whether all pair sums are equal. - Multiply the common pair sum by the number of pairs.

Solution

1. Pair the first and last numbers, then work inward: \(1001+1991=2992\), \(1111+1881=2992\), \(1221+1771=2992\), \(1331+1661=2992\), and \(1441+1551=2992\). 2. There are \(5\) pairs. 3. The total is \(5\times 2992=14{,}960\).

Answer

\(14{,}960\)
Generate shape and number patterns 89
In a sequence, each term is the sum of the two previous terms. The third term is \(12{,}500\), and the fourth term is \(20{,}000\). Find the first, second, and fifth terms.

Hints

- Use subtraction to work backward from a known sum. - The fifth term can be found by applying the rule directly. - Each earlier term equals a later term minus the term beside it.

Solution

1. The fifth term is \(12{,}500 + 20{,}000 = 32{,}500\). 2. The second term is \(20{,}000 - 12{,}500 = 7500\), because the second and third terms add to the fourth. 3. The first term is \(12{,}500 - 7500 = 5000\), because the first and second terms add to the third.

Answer

First term: \(5000\) Second term: \(7500\) Fifth term: \(32{,}500\)
Generate shape and number patterns 90
Each sequence follows the rule that every new term is the sum of the two previous terms. The second term is always \(20{,}000\), while the first term increases by \(1000\) from one sequence to the next. Sequence 1: \(10{,}000, 20{,}000, \ldots\) Sequence 2: \(11{,}000, 20{,}000, \ldots\) Sequence 3: \(12{,}000, 20{,}000, \ldots\) Sequence 4: \(13{,}000, 20{,}000, \ldots\) Find the fifth term of each sequence. How do the fifth terms change?

Hints

- Continue each sequence to its fifth term. - Compare the four fifth terms. - Relate the change in the starting term to the change in the fifth term.

Solution

1. Sequence 1 continues \(30{,}000, 50{,}000, 80{,}000\), so its fifth term is \(80{,}000\). 2. Sequence 2 continues \(31{,}000, 51{,}000, 82{,}000\). 3. Sequence 3 continues \(32{,}000, 52{,}000, 84{,}000\). 4. Sequence 4 continues \(33{,}000, 53{,}000, 86{,}000\). 5. The fifth terms increase by \(2000\) from one sequence to the next.

Answer

Fifth terms: \(80{,}000, 82{,}000, 84{,}000, 86{,}000\) They increase by \(2000\) each time.
Generate shape and number patterns 91
Continue each sequence through the fifth term. Every new term is the sum of the two previous terms. The first term is always \(50{,}000\), while the second term increases by \(10{,}000\). a) \(50{,}000, 10{,}000, \ldots\) b) \(50{,}000, 20{,}000, \ldots\) c) \(50{,}000, 30{,}000, \ldots\) d) \(50{,}000, 40{,}000, \ldots\) By how much does the fifth term increase from one sequence to the next?

Hints

- Add the two most recent terms to find each new term. - Compare only the fifth terms after completing all four sequences. - Determine how the change in the second starting term affects the fifth term.

Solution

1. Sequence a) is \(50{,}000, 10{,}000, 60{,}000, 70{,}000, 130{,}000\). 2. Sequence b) is \(50{,}000, 20{,}000, 70{,}000, 90{,}000, 160{,}000\). 3. Sequence c) is \(50{,}000, 30{,}000, 80{,}000, 110{,}000, 190{,}000\). 4. Sequence d) is \(50{,}000, 40{,}000, 90{,}000, 130{,}000, 220{,}000\). 5. The fifth terms differ by \(30{,}000\) each time.

Answer

a) \(50{,}000, 10{,}000, 60{,}000, 70{,}000, 130{,}000\) b) \(50{,}000, 20{,}000, 70{,}000, 90{,}000, 160{,}000\) c) \(50{,}000, 30{,}000, 80{,}000, 110{,}000, 190{,}000\) d) \(50{,}000, 40{,}000, 90{,}000, 130{,}000, 220{,}000\) The fifth term increases by \(30{,}000\) from one sequence to the next.
Generate shape and number patterns 92
The terms shown are \(5, 15, 10, 30, 25, 75, \ldots\). Find a repeating two-step rule that fits these terms. Use your rule to write the next five terms.

Hints

- The same operation does not happen at every step. - Compare odd-numbered changes with even-numbered changes. - State a two-step rule that works for every transition shown before extending it.

Solution

1. A repeating rule that fits is “multiply by \(3\), then subtract \(5\).” 2. Continue from \(75\): \(75-5=70\), \(70\times3=210\), \(210-5=205\), \(205\times3=615\), and \(615-5=610\).

Answer

One repeating rule that fits is to alternate multiplying by \(3\) and subtracting \(5\). The next five terms are \(70, 210, 205, 615, 610\).
Generate shape and number patterns 93
Create a number pattern using these rules: - If the current number is odd, multiply it by \(3\) and add \(1\). - If the current number is even, divide it by \(2\). Start with \(13\). List every term until the pattern first reaches \(1\). How many operations are needed?

Hints

- Decide whether each current term is odd or even before choosing a rule. - Record every new term so none are skipped. - Count operations, not terms.

Solution

1. Apply the rule to each term: \(13\times3+1=40\), \(40\div2=20\), \(20\div2=10\), \(10\div2=5\), \(5\times3+1=16\), \(16\div2=8\), \(8\div2=4\), \(4\div2=2\), and \(2\div2=1\). 2. The sequence is \(13, 40, 20, 10, 5, 16, 8, 4, 2, 1\). 3. There are \(9\) operations between the starting term and \(1\).

Answer

Sequence: \(13, 40, 20, 10, 5, 16, 8, 4, 2, 1\) Operations: \(9\)
Generate shape and number patterns 94
Create a number pattern using these rules: - If the number is less than \(20\), double it. - If the number is \(20\) or greater, subtract \(7\). Start with \(5\). Continue until a number appears for the second time. List the terms through that repetition. Which number repeats first?

Hints

- Use the second rule when the term is exactly \(20\). - Keep a complete list of the terms. - Compare each new term with every earlier term.

Solution

1. Apply the correct rule to each term: \(5\times2=10\), \(10\times2=20\), \(20-7=13\), \(13\times2=26\), \(26-7=19\), \(19\times2=38\), \(38-7=31\), \(31-7=24\), \(24-7=17\), \(17\times2=34\), \(34-7=27\), and \(27-7=20\). 2. The sequence is \(5, 10, 20, 13, 26, 19, 38, 31, 24, 17, 34, 27, 20\). 3. The first repeated number is \(20\).

Answer

Sequence: \(5, 10, 20, 13, 26, 19, 38, 31, 24, 17, 34, 27, 20\) First repeated number: \(20\)
Generate shape and number patterns 95
A number machine uses these rules: - If a number ends in \(0\), remove the final zero. This is the same as dividing by \(10\). - If a number does not end in \(0\), add \(6\). a) Starting with \(14\), list the first eight terms. b) Describe the pattern you notice.

Hints

- Count the starting value as the first term. - Apply exactly one rule to create each next term. - Look for the first term that appears again.

Solution

1. Start with \(14\). Apply the rules to get \(14+6=20\), \(20\div10=2\), \(2+6=8\), \(8+6=14\), \(14+6=20\), \(20\div10=2\), and \(2+6=8\). 2. The first eight terms are \(14, 20, 2, 8, 14, 20, 2, 8\). 3. The four-term cycle \(14, 20, 2, 8\) repeats.

Answer

a) \(14, 20, 2, 8, 14, 20, 2, 8\) b) The pattern repeats every four terms.
Generate shape and number patterns 96
Study the multiplication equations. Use a simple regular rule that fits the shown equations for the continuation tasks. \(9 \times 7\) \(9 \times 77\) \(9 \times 777\) a) Calculate the three products. b) Describe the digit pattern in the products. c) Under the same simple rule, write the fifth equation and product without using the standard multiplication algorithm.

Hints

- Compare the first and last digits of the products. - Count the \(7\)s in each factor and the \(9\)s in each product. - Extend the digit rule through the fourth equation before writing the fifth.

Solution

1. The first three products are \(9 \times 7 = 63\), \(9 \times 77 = 693\), and \(9 \times 777 = 6993\). 2. Each product begins with \(6\), ends with \(3\), and has \(9\)s between them. The number of \(9\)s is one less than the number of \(7\)s in the second factor. 3. The fifth second factor is \(77{,}777\), so the fifth equation is \(9 \times 77{,}777 = 699{,}993\).

Answer

a) \(63, 693, 6993\) b) Each product begins with \(6\), ends with \(3\), and gains one more \(9\) in the middle. c) \(9 \times 77{,}777 = 699{,}993\)
Generate shape and number patterns 97
Study this pattern of sums: Row 1: \(1\) Row 2: \(1+2\) Row 3: \(1+2+3\) Row 4: \(1+2+3+4\) a) Find the results for rows \(1\) through \(6\). b) What is the result in row \(10\)? c) In which row is the result \(78\)? Explain how you found it.

Hints

- How does each new row differ from the row above? - Keep a running sum rather than starting each addition again. - For part c), use your result from part b) and look ahead to the next rows.

Solution

1. Each row adds the next whole number, so the results for rows \(1\) through \(6\) are \(1,3,6,10,15,21\). 2. Keep adding the next number: rows \(7\) through \(10\) total \(28,36,45,55\). Thus row \(10\) totals \(55\). 3. The next two totals are \(55+11=66\) and \(66+12=78\), so row \(12\) totals \(78\).

Answer

a) \(1,3,6,10,15,21\) b) \(55\) c) Row \(12\), because rows \(11\) and \(12\) add \(11\) and \(12\) to the previous totals.
Generate shape and number patterns 98
A number machine multiplies each digit by itself and then adds the products. For example, \(13\) becomes \(1\times1+3\times3=10\), and \(10\) becomes \(1\times1+0\times0=1\). Start with \(49\). Repeat the rule until you reach \(1\). List the number chain and state how many steps it takes.

Hints

- Apply the rule to every digit in the current number. - Record each result before repeating the rule. - Count the operations between numbers, not the number of terms.

Solution

1. \(4\times4+9\times9=16+81=97\). 2. \(9\times9+7\times7=81+49=130\). 3. \(1\times1+3\times3+0\times0=1+9+0=10\). 4. \(1\times1+0\times0=1\). 5. The chain is \(49\rightarrow97\rightarrow130\rightarrow10\rightarrow1\), which takes \(4\) steps.

Answer

Chain: \(49\rightarrow97\rightarrow130\rightarrow10\rightarrow1\) Steps: \(4\)
Generate shape and number patterns 99
Use this number-machine rule: multiply each digit by itself and add the products. Start with \(20\) and apply the rule eight times. List the chain. What do you notice after the eighth step?

Hints

- Apply the rule to each digit, including any zero. - Keep the terms in order. - Compare the eighth result with the starting number.

Solution

1. Apply the rule repeatedly: \(2\times2+0\times0=4\), \(4\times4=16\), \(1\times1+6\times6=37\), \(3\times3+7\times7=58\), \(5\times5+8\times8=89\), \(8\times8+9\times9=145\), \(1\times1+4\times4+5\times5=42\), and \(4\times4+2\times2=20\). 2. The chain is \(20\rightarrow4\rightarrow16\rightarrow37\rightarrow58\rightarrow89\rightarrow145\rightarrow42\rightarrow20\). 3. After eight steps, the chain returns to \(20\), so the cycle repeats.

Answer

Chain: \(20\rightarrow4\rightarrow16\rightarrow37\rightarrow58\rightarrow89\rightarrow145\rightarrow42\rightarrow20\) The chain returns to \(20\) after eight steps and repeats.
Generate shape and number patterns 100
Investigate products with \(25\) and identify a pattern. a) Calculate: \(4 \times 25 = \square\) \(8 \times 25 = \square\) \(12 \times 25 = \square\) b) What happens to the product each time the first factor increases by \(4\)? c) Use the pattern from part b to find \(16 \times 25\) and \(20 \times 25\).

Hints

- Compare consecutive products and determine their difference. - Relate that difference to \(4 \times 25\). - Continue the same change for the next two first factors.

Solution

1. Part a: \(4 \times 25 = 100\), \(8 \times 25 = 200\), and \(12 \times 25 = 300\). 2. Part b: Each time the first factor increases by \(4\), the product increases by \(4 \times 25 = 100\). 3. Part c: Continue the pattern: \(16 \times 25 = 300 + 100 = 400\), and \(20 \times 25 = 400 + 100 = 500\).

Answer

a) \(100\), \(200\), \(300\) b) The product increases by \(100\) each time. c) \(16 \times 25 = 400\) and \(20 \times 25 = 500\)
Generate shape and number patterns 101
Complete the table. Starting from each number, count five steps in the stated direction. <table> <tr> <th>Starting number</th> <th>Direction</th> <th>Step size</th> <th>Step 1</th> <th>Step 2</th> <th>Step 3</th> <th>Step 4</th> <th>Step 5</th> </tr> <tr> <td>\(24{,}500\)</td> <td>forward</td> <td>\(250\)</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> <tr> <td>\(10{,}200\)</td> <td>backward</td> <td>\(40\)</td> <td></td> <td></td> <td></td> <td></td> <td></td> </tr> </table>

Hints

- Use each result as the starting point for the next step. - Add when counting forward and subtract when counting backward. - Check that the difference between consecutive entries is constant.

Solution

1. For the first row, add \(250\) at each step: \(24{,}750, 25{,}000, 25{,}250, 25{,}500, 25{,}750\). 2. For the second row, subtract \(40\) at each step: \(10{,}160, 10{,}120, 10{,}080, 10{,}040, 10{,}000\).

Answer

First row: \(24{,}750, 25{,}000, 25{,}250, 25{,}500, 25{,}750\) Second row: \(10{,}160, 10{,}120, 10{,}080, 10{,}040, 10{,}000\)
Generate shape and number patterns 102
The two cube buildings occupy cubes along three perpendicular edges that meet at one corner of each outer box. a) In Building \(1\) and Building \(2\), how many cubes long is each occupied edge? b) A next building uses the same geometric rule inside a \(4 \times 4 \times 4\) box. How many cubes will it contain? Explain how you avoid counting the shared corner cube three times.
Figure for problem 532829

Hints

- Look at where the cubes lie relative to the three edges meeting at one corner. - Extend that same edge structure to side length \(4\). - The corner cube belongs to all three occupied edges, so account for repeated counting.

Solution

1. In Building \(1\), each occupied edge is \(2\) cubes long. In Building \(2\), each occupied edge is \(3\) cubes long. 2. The next building has three occupied edges of length \(4\). Counting all three gives \(4+4+4=12\), but the common corner was counted three times and should count once. 3. Subtract the two extra counts of the shared corner: \(12-2=10\) cubes.

Answer

a) Building \(1\) has occupied edge length \(2\); Building \(2\) has occupied edge length \(3\). b) The next building contains \(10\) cubes. Three length-4 edges would give \(4+4+4=12\) counts, but the common corner is counted three times and should be counted once, so subtract the two extra counts: \(12-2=10\).
Generate shape and number patterns 103
The diagrams show Lucas’s cube staircase on Days \(1\), \(2\), and \(3\). Describe the vertical stack heights in each shown staircase, listing them from tallest to shortest. If the same staircase-growth rule continues, what will the stack heights be on Day \(5\), and how many cubes will Day \(5\) contain altogether?
Figure for problem 532948

Hints

- Read each column of the cube diagrams as a vertical stack. - Describe the sequence of stack heights, not only the total number of cubes. - Extend the staircase shape to five stacks before adding the cubes.

Solution

1. The stack heights are \(1\) on Day \(1\); \(2,1\) on Day \(2\); and \(3,2,1\) on Day \(3\). 2. The geometric rule adds a new tallest stack while keeping a descending staircase of consecutive heights. 3. Day \(5\) therefore has stack heights \(5,4,3,2,1\). 4. The total is \(5+4+3+2+1=15\) cubes.

Answer

Day \(1\): stack heights \(1\). Day \(2\): \(2,1\). Day \(3\): \(3,2,1\). The staircase adds a new tallest stack while keeping consecutive descending heights. Day \(5\) therefore has stack heights \(5,4,3,2,1\) and contains \(15\) cubes altogether.
Generate shape and number patterns 104
Some bricks are missing from these number walls. Every brick is the sum of the two bricks directly below it. Which walls can be completed using whole numbers? Select them and find the missing numbers.
Figure for problem 535251

Hints

- Use the number-wall rule to trace how a missing bottom value affects the bricks above it. - Before calculating a missing value, check whether the fixed outside values already make the target impossible. - Verify any candidate by rebuilding the wall upward.

Solution

1. Wall a): \(80-10-20=50\). The middle bottom brick must contribute twice, so it is \(25\). The middle row is \(35\) and \(45\). 2. Wall b): The outside bottom bricks already total \(45+40=85\), which is greater than the top brick \(80\), so no whole-number middle value can work. 3. Wall c): \(80-25-25=30\), so the middle bottom brick is \(15\). The middle row is \(40\) and \(40\). 4. Wall d): The outside bottom bricks already total \(41+42=83\), which is greater than \(80\), so no whole-number middle value can work.

Answer

Walls a) and c) can be completed. a) The middle bottom brick is \(25\), and the middle row is \(35,45\). c) The middle bottom brick is \(15\), and the middle row is \(40,40\). Walls b) and d) cannot be completed using whole numbers.
Generate shape and number patterns 105
Compare the two number walls. If every bottom-row value is doubled, what happens to the top value?
Figure for problem 535324

Hints

- Calculate the top value in each wall. - Compare corresponding bottom-row values in a) and b). - Check whether the same relationship holds for the top values.

Solution

1. In wall a), the second row is \(10 + 25 = 35\) and \(25 + 15 = 40\), so the top is \(35 + 40 = 75\). 2. In wall b), the second row is \(20 + 50 = 70\) and \(50 + 30 = 80\), so the top is \(70 + 80 = 150\). 3. Since \(150 = 2 \times 75\), doubling every bottom-row value doubles the top value.

Answer

The top value also doubles, from \(75\) to \(150\).
Generate shape and number patterns 106
Complete the number wall. Then add \(2\) to every bottom-row value. By how much does the top value increase?
Figure for problem 535328

Hints

- First calculate the original top value. - Build the new wall with \(7\) in each bottom brick. - Compare the two top values.

Solution

1. The original wall has second row \(10, 10, 10\), third row \(20, 20\), and top value \(40\). 2. After adding \(2\), the bottom row becomes \(7, 7, 7, 7\). The new rows are \(14, 14, 14\), then \(28, 28\), with \(56\) at the top. 3. The increase is \(56 - 40 = 16\). 4. Equivalently, increasing each of four bottom bricks by \(1\) increases the top by \(8\), so an increase of \(2\) raises the top by \(2 \times 8 = 16\).

Answer

The top value increases by \(16\).
Generate shape and number patterns 107
Fill the missing bottom bricks in the number wall shown. Every brick is the sum of the two bricks directly below it. Find one possible whole-number solution.
Figure for problem 535359

Hints

- Read the fixed middle and top values from the wall. - Trace how many times the middle bottom brick contributes to the top. - More than one pair of outside values may satisfy the target.

Solution

1. The fixed middle bottom brick is \(40\), and it contributes to both bricks above it, so its total contribution to the top is \(2\times40=80\). 2. The top is \(100\), so the two outside bottom bricks must total \(100-80=20\). 3. One possible pair is \(12\) and \(8\), giving the bottom row \(12,40,8\). 4. Check: the next row is \(52,48\), and \(52+48=100\).

Answer

One possible bottom row is \(12,40,8\). Any two whole-number outside values with sum \(20\) also work.
Generate shape and number patterns 108
Jordan says, “If I increase the bottom-left brick of a four-brick number wall by \(10\), the top value also increases by exactly \(10\).” Is Jordan correct? Calculate wall b) to test the claim.
Figure for problem 535363

Hints

- Complete wall b) from the bottom row upward. - Compare its top value with \(500\).

Solution

1. Wall a) has top value \(500\). 2. In wall b), the second row is \(110 + 50 = 160\), \(50 + 50 = 100\), and \(50 + 100 = 150\). 3. The third row is \(160 + 100 = 260\) and \(100 + 150 = 250\). 4. The new top is \(260 + 250 = 510\). 5. Since \(510 - 500 = 10\), Jordan is correct.

Answer

Yes. The top value changes from \(500\) to \(510\), an increase of \(10\).
Generate shape and number patterns 109
Complete both number walls and compare their top values. What happens when one inner bottom brick is increased by \(1\)?
Figure for problem 535384

Hints

- Calculate the top value of each wall. - Trace how often the changed value contributes to bricks above it.

Solution

1. In wall a), the second row is \(20, 20, 20\), the third row is \(40, 40\), and the top is \(80\). 2. In wall b), the second row is \(21, 21, 20\), the third row is \(42, 41\), and the top is \(83\). 3. The top increases by \(83 - 80 = 3\). The changed inner brick contributes along three paths to the top.

Answer

The top value increases by \(3\), from \(80\) to \(83\).
Generate shape and number patterns 110
The panels show a growing rectangle pattern on a unit grid. Each grid cell represents one square unit. Find the dimensions of Stage \(4\), and determine how many unit squares it contains. Explain the two changes that occur from one stage to the next.
Figure for problem 554398

Hints

- Count the width and height of each displayed rectangle separately. - Compare how both dimensions change from panel to panel. - Use the predicted dimensions to count unit squares efficiently.

Solution

1. The dimensions are \(1\times2\), \(2\times3\), and \(3\times4\). 2. Each stage increases both dimensions by \(1\), so Stage \(4\) is \(4\times5\). 3. It contains \(4\times5=20\) unit squares.

Answer

Stage \(4\) is \(4\times5\) and contains \(20\) unit squares. Both dimensions increase by \(1\) each stage.
Generate shape and number patterns 111
Each stage adds one more square to a row of matchstick squares. Count the shared sides carefully. How many matchsticks will Stage \(5\) need? Explain what changes each time a square is added.
Figure for problem 554399

Hints

- Count every drawn side once, including shared sides. - Compare how many matchsticks appear in one stage and the next. - Decide how many new matchsticks one additional square needs.

Solution

1. The first three stages use \(4\), \(7\), and \(10\) matchsticks. 2. Each added square shares one side with the previous figure, so it needs just \(3\) new matchsticks. 3. Stage \(4\) uses \(10+3=13\) matchsticks and Stage \(5\) uses \(13+3=16\).

Answer

Stage \(5\) needs \(16\) matchsticks. Each new square adds \(3\) matchsticks because one side is shared.
Generate shape and number patterns 112
The three rectangles follow a pattern in both size and orientation. Each grid interval is \(1\) unit. Describe both rules, then state the dimensions and orientation of Stage \(4\).
Figure for problem 554400

Hints

- Track the long side length separately from the direction of the rectangle. - Look for one rule about size and another rule about orientation. - Both rules must be continued to determine Stage \(4\).

Solution

1. The long side lengths are \(2,3,4\) units, so the long side increases by \(1\) each stage. 2. The rectangles alternate horizontal, vertical, horizontal. 3. Stage \(4\) therefore has dimensions \(1\times5\) and is vertical.

Answer

The long side increases by \(1\) unit and the orientation alternates. Stage \(4\) is a vertical \(1\times5\) rectangle.
Generate shape and number patterns 113
The cube diagrams show square, one-layer stages of a growing pattern. If the pattern continues, how many cubes will Stage \(5\) contain? Explain how the side length and total number of cubes are related.
Figure for problem 554401

Hints

- Think of the blocks as one flat square layer. - Compare the number of cubes along a side with the stage number. - Count the cubes in rows and columns.

Solution

1. The displayed stages are square layers with \(1\), \(2\), and \(3\) cubes on each side. 2. Stage \(4\) would have \(4\) cubes on each side. Stage \(5\) has \(5\) cubes on each side. 3. There are \(5\) rows of \(5\), so Stage \(5\) contains \(5\times5=25\) cubes.

Answer

Stage \(5\) contains \(25\) cubes. Its square layer has \(5\) cubes on each side, giving \(5\times5=25\).
Generate shape and number patterns 114
The diagrams show Stage \(1\) and Stage \(3\) of a one-layer cross pattern made from cubes. Candidates A and B are two possible missing Stage \(2\) shapes. Candidates A and B contain the same number of cubes. Which candidate continues the geometric pattern? Describe how each arm changes from Stage \(1\) to Stage \(2\) to Stage \(3\).
Figure for problem 554402

Hints

- Do not decide by counting cubes; the two candidates have equal cube counts. - Compare the shape and length of each arm with Stages \(1\) and \(3\). - The missing stage should be geometrically between the two shown crosses.

Solution

1. Stage \(1\) has one cube extending from the center in each of four directions. 2. Stage \(3\) has three cubes extending from the center in each direction. 3. The missing stage must therefore have two cubes extending from the center along each arm. Candidate A has that cross structure; candidate B is a solid square even though it uses the same number of cubes. 4. Thus Candidate A is Stage \(2\).

Answer

Candidate A. Each of the four arms grows by one cube from one stage to the next.
Generate shape and number patterns 115
Stages \(1\), \(2\), and \(3\) show a shape pattern. Candidates A and B are possible next shapes. Which candidate continues the pattern? State the visual rule that determines your choice.
Figure for problem 554404

Hints

- Count a structural feature of each stage rather than comparing size or color. - Write the counts for Stages \(1\), \(2\), and \(3\). - Choose the candidate whose corresponding count continues that pattern.

Solution

1. Stage \(1\) has \(3\) sides, Stage \(2\) has \(4\) sides, and Stage \(3\) has \(5\) sides. 2. The rule adds one side at each stage. 3. Candidate A has \(6\) sides, while Candidate B has \(3\), so Candidate A continues the pattern.

Answer

Candidate A. The number of sides increases by \(1\) at each stage: \(3,4,5,6\).
Generate shape and number patterns 116
This sequence decreases. Give a simple regular rule that fits all the shown terms, then use it to fill in the three missing terms. \(880, 878, 874, 868, \ldots, \ldots, \ldots, 824\)

Hints

- Since the terms decrease, examine how much is subtracted each time. - Compare the successive decreases. - Consider whether the amounts subtracted follow the even-number pattern.

Solution

1. The decreases are \(880-878=2\), \(878-874=4\), and \(874-868=6\). 2. The sequence subtracts consecutive even numbers: \(2, 4, 6, 8, \ldots\). 3. Continue with \(868-8=860\), \(860-10=850\), and \(850-12=838\). 4. The next step is \(838-14=824\), which matches the final term.

Answer

The missing numbers are \(860, 850,\) and \(838\). One simple rule that fits: subtract consecutive even numbers \(2, 4, 6, 8, 10, 12, 14, \ldots\).
Generate shape and number patterns 117
Give a simple repeating rule that fits all the shown terms, then use that rule to continue the number pattern with three more terms. \(2500, 5000, 4000, 8000, 7000, \ldots\)

Hints

- Compare the first term with the second. - Then compare the second term with the third. - Look for a repeating two-step rule.

Solution

1. The first step is \(2500 \times 2 = 5000\). 2. The second step is \(5000 - 1000 = 4000\). 3. The same two-step rule repeats: multiply by \(2\), then subtract \(1000\). 4. Continue: \(7000 \times 2 = 14{,}000\), \(14{,}000 - 1000 = 13{,}000\), and \(13{,}000 \times 2 = 26{,}000\).

Answer

Next terms: \(14{,}000, 13{,}000, 26{,}000\) One simple rule that fits: Alternate multiplying by \(2\) and subtracting \(1000\).
Generate shape and number patterns 118
A repeated operation adds \(1\), \(10\), \(100\), \(1000\), \(10{,}000\), and \(100{,}000\) to a starting number. a) Apply the complete operation twice to \(345{,}123\). What is the final number? b) Starting at \(100{,}000\), how many complete operations can you apply without going above \(1{,}000{,}000\)?

Hints

- First find the total amount added by one complete operation. - For part a), apply that same addition twice in succession. - For part b), keep the repeated-addition pattern visible and stop before the cap is exceeded.

Solution

1. One complete operation adds \(1+10+100+1000+10{,}000+100{,}000=111{,}111\). 2. For a), one operation gives \(345{,}123+111{,}111=456{,}234\). Applying it again gives \(456{,}234+111{,}111=567{,}345\). 3. For b), repeated additions give \(211{,}111\), \(322{,}222\), \(433{,}333\), \(544{,}444\), \(655{,}555\), \(766{,}666\), \(877{,}777\), and \(988{,}888\) after eight operations. 4. One more operation gives \(1{,}099{,}999\), which is above \(1{,}000{,}000\). Therefore, \(8\) complete operations are possible.

Answer

a) \(567{,}345\) b) \(8\) times
Generate shape and number patterns 119
Using a simple regular rule that fits the three shown equations, continue the pattern for two more rows and explain the digit relationship you notice. \(10{,}203+19{,}998=30{,}201\) \(20{,}304+19{,}998=40{,}302\) \(30{,}405+19{,}998=50{,}403\)

Hints

- Compare corresponding digits in the first addends. - Find the amount added from one row to the next. - Use the same change to predict the next sums. - Compare the digit order in each first addend and its sum.

Solution

1. The first addend increases by \(10{,}101\) in each row, so the sum also increases by \(10{,}101\). 2. The next two rows are \(40{,}506+19{,}998=60{,}504\) and \(50{,}607+19{,}998=70{,}605\). 3. In every row, the sum contains the digits of the first addend in reverse order.

Answer

\(40{,}506+19{,}998=60{,}504\) \(50{,}607+19{,}998=70{,}605\) The digits of each sum are the digits of the first addend in reverse order.
Generate shape and number patterns 120
Using a simple regular rule that fits the three shown equations, calculate the sums, write the next equation, and determine how much the sum increases each time. \(12{,}345+23{,}456\) \(23{,}456+34{,}567\) \(34{,}567+45{,}678\)

Hints

- Calculate each sum carefully using place value. - Compare the first addends in consecutive rows. - Compare the second addends in consecutive rows. - Combine the two changes to predict how the sums change.

Solution

1. The sums are \(12{,}345+23{,}456=35{,}801\), \(23{,}456+34{,}567=58{,}023\), and \(34{,}567+45{,}678=80{,}245\). 2. Each addend increases by \(11{,}111\), so the next equation is \(45{,}678+56{,}789=102{,}467\). 3. Since both addends increase by \(11{,}111\), the sum increases by \(22{,}222\) each time.

Answer

The sums are \(35{,}801\), \(58{,}023\), and \(80{,}245\). The next equation is \(45{,}678+56{,}789=102{,}467\). The sum increases by \(22{,}222\) each time.
Generate shape and number patterns 121
Study the three shown equations and give a simple regular rule that fits them. \(9\times9+7=88\) \(98\times9+6=888\) \(987\times9+5=8888\) a) Using that rule, write and evaluate the next equation. b) If the same rule is continued for one more row, predict the next result without carrying out a five-digit multiplication. How many digits would that result have?

Hints

- Track how the digits in the first factor change. - Track how the added number changes. - For part b), use the pattern in the results rather than calculating another large product.

Solution

1. The first factor appends the next lower digit each time, while the added number decreases by \(1\). 2. The fourth equation is \(9876\times9+4=88{,}888\). 3. The results gain one additional digit \(8\) in each row. Therefore, the next result would be \(888{,}888\), which has \(6\) digits, without evaluating the next multiplication.

Answer

a) A simple rule that fits appends the next lower digit to the first factor while the added number decreases by \(1\). Thus \(9876\times9+4=88{,}888\). b) The result pattern gains one additional digit \(8\) each row, so the next result is \(888{,}888\), with \(6\) digits.
Generate shape and number patterns 122
Two four-digit palindromes of the forms \(abba\) and \(baab\), made from the same two digits, differ by exactly \(2673\). Which two digits could have been used? Find three different digit pairs.

Hints

- Start with two digits that differ by \(1\) and find the palindrome difference. - Compare \(2673\) with that smallest difference. - List digit pairs from \(1\) through \(9\) with the required difference. - Check three pairs by subtraction.

Solution

1. When the two digits differ by \(1\), the two palindromes differ by \(891\). 2. Since \(3\times 891=2673\), the two chosen digits must differ by \(3\). 3. Possible pairs are \((1,4)\), \((2,5)\), \((3,6)\), \((4,7)\), \((5,8)\), and \((6,9)\). 4. For example, \(4114-1441=2673\), \(5225-2552=2673\), and \(6336-3663=2673\).

Answer

Any three digit pairs that differ by \(3\) are valid. Examples are \((1,4)\), \((2,5)\), and \((3,6)\).
Generate shape and number patterns 123
A hundreds chart has ten numbers in each column. <table><tbody><tr><td>1</td><td>2</td><td>3</td><td>4</td><td>5</td><td>6</td><td>7</td><td>8</td><td>9</td><td>10</td></tr><tr><td>11</td><td>12</td><td>13</td><td>14</td><td>15</td><td>16</td><td>17</td><td>18</td><td>19</td><td>20</td></tr><tr><td>21</td><td>22</td><td>23</td><td>24</td><td>25</td><td>26</td><td>27</td><td>28</td><td>29</td><td>30</td></tr><tr><td>31</td><td>32</td><td>33</td><td>34</td><td>35</td><td>36</td><td>37</td><td>38</td><td>39</td><td>40</td></tr><tr><td>41</td><td>42</td><td>43</td><td>44</td><td>45</td><td>46</td><td>47</td><td>48</td><td>49</td><td>50</td></tr><tr><td>51</td><td>52</td><td>53</td><td>54</td><td>55</td><td>56</td><td>57</td><td>58</td><td>59</td><td>60</td></tr><tr><td>61</td><td>62</td><td>63</td><td>64</td><td>65</td><td>66</td><td>67</td><td>68</td><td>69</td><td>70</td></tr><tr><td>71</td><td>72</td><td>73</td><td>74</td><td>75</td><td>76</td><td>77</td><td>78</td><td>79</td><td>80</td></tr><tr><td>81</td><td>82</td><td>83</td><td>84</td><td>85</td><td>86</td><td>87</td><td>88</td><td>89</td><td>90</td></tr><tr><td>91</td><td>92</td><td>93</td><td>94</td><td>95</td><td>96</td><td>97</td><td>98</td><td>99</td><td>100</td></tr></tbody></table> 1. Find the sum of the first column: \(1,11,21,31,41,51,61,71,81,91\). 2. Find the sum of the second column: \(2,12,22,32,42,52,62,72,82,92\). 3. How much greater is the second column sum? Explain why. 4. Find the sum of the tenth column, \(10,20,\dots,100\), without adding all ten numbers individually. 5. Add the ten column sums to find the total of the hundreds chart.

Hints

- Compare corresponding entries in the first two columns. - Use the repeated change to predict later column sums. - Count how many steps separate the first and tenth columns. - Pair the first and last column sums when finding the final total.

Solution

1. The first column sum is \(1+11+21+31+41+51+61+71+81+91=460\). 2. The second column sum is \(2+12+22+32+42+52+62+72+82+92=470\). 3. The second sum is \(10\) greater because each of its ten entries is \(1\) greater. 4. Each column sum is \(10\) greater than the previous one. The tenth column sum is \(460+9\times 10=550\). 5. The column sums are \(460,470,480,490,500,510,520,530,540,550\), and their total is \(5050\).

Answer

1. \(460\) 2. \(470\) 3. It is \(10\) greater because all ten entries are \(1\) greater. 4. \(550\) 5. \(5050\)
Generate shape and number patterns 124
On a hundreds chart, the numbers go up by \(1\) as you move right and by \(10\) as you move down. This is a \(3\times3\) block from the chart: <table><tbody><tr><td>14</td><td>15</td><td>16</td></tr><tr><td>24</td><td>25</td><td>26</td></tr><tr><td>34</td><td>35</td><td>36</td></tr></tbody></table> a) Add its nine numbers. b) Multiply the center number by \(9\). What do you notice? c) Make a different \(3\times3\) block with \(58\) in the center. Does the same pattern work? d) Explain why this happens for any such block.

Hints

- Look at the numbers opposite each other across the center. - For a new block, move left or right by \(1\), and up or down by \(10\), from its center. - Can you group the eight outside numbers into pairs with the same sum?

Solution

1. The first block has a sum of \(14+15+16+24+25+26+34+35+36=225\). 2. Its center is \(25\), and \(9\times25=225\). The sum is nine times the center. 3. The block centered at \(58\) has rows \(47,48,49\), \(57,58,59\), and \(67,68,69\). Its sum is \(522=9\times58\). 4. Each pair of numbers directly opposite the center has a sum of twice the center: in the first block, \(14+36=50\), \(15+35=50\), \(16+34=50\), and \(24+26=50\). 5. Four pairs make eight copies of the center. Adding the center itself makes nine copies. This works in every \(3\times3\) block on a hundreds chart.

Answer

a) \(225\) b) \(225\); it equals the sum from part a). c) Yes. The second block has sum \(522=9\times58\). d) The four opposite pairs each total twice the center, and the center adds one more copy. So the nine-number sum is always nine times the center.
Generate shape and number patterns 125
For four-digit repeating-block numbers of the forms \(abab\) and \(baba\), the difference depends on the difference between digits \(a\) and \(b\). a) Find the number difference when \(a=6\) and \(b=1\). b) Find every ordered digit pair \((a,b)\), with both digits from \(1\) through \(9\) and \(a>b\), for which the number difference is \(1818\). c) What is the smallest possible positive difference between two such numbers?

Hints

- First test a digit difference of \(1\). - Compare \(1818\) with the resulting number difference. - List all ordered digit pairs with the required difference. - Use the smallest possible positive digit difference for part c).

Solution

1. For \(a=6\) and \(b=1\), \(6161-1616=4545\). 2. A digit difference of \(1\) produces a number difference of \(909\). Since \(1818=2\times 909\), the digits must differ by \(2\). 3. The ordered pairs are \((3,1)\), \((4,2)\), \((5,3)\), \((6,4)\), \((7,5)\), \((8,6)\), and \((9,7)\). 4. The smallest positive digit difference is \(1\), so the smallest positive number difference is \(909\).

Answer

a) \(4545\) b) \((3,1),(4,2),(5,3),(6,4),(7,5),(8,6),(9,7)\) c) \(909\)
Generate shape and number patterns 126
A sequence begins with \(6500\) and \(9000\). Each new term is the sum of the two previous terms. What is the first term greater than \(100{,}000\), and what position does it have in the sequence?

Hints

- Number the terms as you build the sequence. - Add the two most recent terms each time. - Stop only when a term is greater than \(100{,}000\).

Solution

1. Continue the sequence: \(6500, 9000, 15{,}500, 24{,}500, 40{,}000, 64{,}500, 104{,}500\). 2. The sixth term, \(64{,}500\), is below \(100{,}000\). 3. The seventh term, \(104{,}500\), is greater than \(100{,}000\), so it is the first term that meets the condition.

Answer

The seventh term is the first one greater than \(100{,}000\). It is \(104{,}500\).
Generate shape and number patterns 127
Two students build sequences in which each new term is the sum of the two previous terms. Starting with \(100{,}000\) and \(100{,}000\), the fifth term is \(500{,}000\). Now each student increases exactly one starting term by \(1\): Luke: \(100{,}001, 100{,}000, \ldots\) Mia: \(100{,}000, 100{,}001, \ldots\) Who gets the greater fifth term? Calculate both sequences to justify your answer.

Hints

- Continue both sequences carefully through the fifth term. - Track how often each starting term contributes to later terms. - Compare the two fifth terms only after both sequences are complete.

Solution

1. Luke's sequence is \(100{,}001, 100{,}000, 200{,}001, 300{,}001, 500{,}002\). 2. Mia's sequence is \(100{,}000, 100{,}001, 200{,}001, 300{,}002, 500{,}003\). 3. Since \(500{,}003 > 500{,}002\), Mia gets the greater fifth term.

Answer

Mia gets the greater fifth term: \(500{,}003\), compared with Luke's \(500{,}002\).
Generate shape and number patterns 128
The terms shown are \(2, 3, 6, 11, 18, \ldots\). Find a simple rule for the changes between terms that fits the sequence. Use that rule to find the next five terms.

Hints

- Write the difference between each neighboring pair. - Look for a simple pattern in those differences. - Continue the difference pattern first, then use it to extend the original sequence.

Solution

1. The differences are \(1,3,5,7\). 2. A simple rule that fits is to add consecutive odd numbers. The next differences are \(9,11,13,15,17\). 3. Adding them in order gives \(27,38,51,66,83\).

Answer

One simple rule that fits is to add consecutive odd numbers: \(1,3,5,7,9,\ldots\). The next five terms are \(27, 38, 51, 66, 83\).
Generate shape and number patterns 129
In a number pattern, each term is the sum of the two terms before it. Two consecutive terms are \(7\) and \(11\). Find the two terms immediately before \(7\) and the two terms immediately after \(11\).

Hints

- Add \(7\) and \(11\) to move forward. - Use subtraction to reverse the addition rule. - Check every group of three consecutive terms.

Solution

1. Find the next terms by adding: \(7+11=18\), then \(11+18=29\). 2. Work backward using subtraction. The term before \(7\) is \(11-7=4\). The term before \(4\) is \(7-4=3\). 3. Check the pattern: \(3; 4; 7; 11; 18; 29\). Each term after the first two is the sum of the previous two.

Answer

Before \(7\): \(3\) and \(4\) After \(11\): \(18\) and \(29\)
Generate shape and number patterns 130
Leo and a friend play “Reach \(32\).” They start at \(0\) and take turns adding \(1\), \(2\), \(3\), \(4\), or \(5\) to the total. The player who reaches exactly \(32\) wins. a) Leo goes first and adds \(2\). Why is that a good first move? b) What should Leo add if his friend adds \(1\)? What if his friend adds \(4\)? Explain how Leo can answer any allowed move. c) What totals should Leo reach after his turns to make sure he wins?

Hints

- Work backward from the winning total in equal jumps. - Can two players' moves always make the same combined increase? - Check that each reply you propose stays between the allowed numbers.

Solution

1. Leo can make each pair of turns increase the total by \(6\): if his friend adds \(1\), Leo adds \(5\); if the friend adds \(2\), Leo adds \(4\); if the friend adds \(3\), Leo adds \(3\); if the friend adds \(4\), Leo adds \(2\); and if the friend adds \(5\), Leo adds \(1\). 2. Starting with \(2\) and increasing by \(6\) after each pair of turns gives \(2,8,14,20,26,32\). 3. Each of Leo's replies is an allowed move, and his friend cannot reach \(32\) first because the previous target is \(26\) and the friend can add at most \(5\).

Answer

a) Leo can then keep increasing his total by \(6\) after every pair of turns. b) Add \(5\) after \(1\); add \(2\) after \(4\). Always make the two moves add to \(6\). c) \(2,8,14,20,26,32\)
Generate shape and number patterns 131
Two players take turns taking \(1\) or \(2\) pieces of candy from a bowl holding \(21\) pieces. The player who takes the last piece wins. If both play as well as they can, which player can make sure of winning? Explain the moves.

Hints

- Try playing with fewer candies to find a repeating winning position. - What total could the two players always remove together? - Work back from the empty bowl in equal steps.

Solution

1. Every two turns can remove \(3\) pieces if the second player takes \(2\) after the first player takes \(1\), and takes \(1\) after the first player takes \(2\). 2. Starting with \(21\), the second player can leave \(18,15,12,9,6,3\), and finally \(0\) pieces after their turns. 3. The first player cannot take all \(3\) remaining pieces in one turn, so the second player can always take the last piece.

Answer

The second player can make sure of winning. Take \(2\) pieces after the first player takes \(1\), and take \(1\) after the first player takes \(2\). This removes \(3\) pieces every two turns.
Generate shape and number patterns 132
Study this sequence of expressions: 1. \(2-1\) 2. \(4-3+2-1\) 3. \(6-5+4-3+2-1\) 4. \(8-7+6-5+4-3+2-1\) a) Find the results of the first four rows. Describe the pattern. b) Write the expression for row \(6\) and find its result. c) Which row has a result of \(25\)?

Hints

- Group each even number with the odd number immediately after it. - Each pair has the same value. - Count the number of pairs in each row.

Solution

1. a) Group consecutive pairs: \((2-1)=1\), \((4-3)+(2-1)=2\), \((6-5)+(4-3)+(2-1)=3\), and \((8-7)+(6-5)+(4-3)+(2-1)=4\). The result equals the row number. 2. b) Row \(6\) is \(12-11+10-9+8-7+6-5+4-3+2-1\). It contains six pairs that each equal \(1\), so the result is \(6\). 3. c) Because the result equals the row number, row \(25\) has a result of \(25\).

Answer

a) \(1, 2, 3, 4\); the result equals the row number. b) \(12-11+10-9+8-7+6-5+4-3+2-1=6\) c) Row \(25\)
Generate shape and number patterns 133
Study this sequence of calculations: 1. \(100-1=99\) 2. \(100-(1+2)=97\) 3. \(100-(1+2+3)=94\) 4. \(100-(1+2+3+4)=90\) a) Find the results for rows \(5\) and \(6\). b) In which row is the result less than \(80\) for the first time? c) What is the result in row \(10\)?

Hints

- Each row adds one more number inside the parentheses. - Use the previous sum to find the next sum. - Compare each result with \(80\).

Solution

1. a) Row \(5\) subtracts \(1+2+3+4+5=15\), so the result is \(100-15=85\). Row \(6\) subtracts \(15+6=21\), so the result is \(100-21=79\). 2. b) Row \(5\) gives \(85\), and row \(6\) gives \(79\). Therefore, row \(6\) is the first result less than \(80\). 3. c) The sum from \(1\) through \(10\) is \(55\), so row \(10\) gives \(100-55=45\).

Answer

a) Row \(5\): \(85\); row \(6\): \(79\) b) Row \(6\) c) \(45\)
Generate shape and number patterns 134
A “happy number” reaches \(1\) after repeatedly multiplying each digit by itself and adding the products. Test \(13\), \(14\), and \(15\). Which are happy numbers? Show each chain until it reaches \(1\) or repeats a number.

Hints

- Work with one starting number at a time. - Record every term in each chain. - Stop when the chain reaches \(1\) or when a term appears for the second time.

Solution

1. For \(13\): \(13\rightarrow10\rightarrow1\). Therefore, \(13\) is happy. 2. For \(14\): \(14\rightarrow17\rightarrow50\rightarrow25\rightarrow29\rightarrow85\rightarrow89\rightarrow145\rightarrow42\rightarrow20\rightarrow4\rightarrow16\rightarrow37\rightarrow58\rightarrow89\). The term \(89\) repeats, so the chain enters a cycle and never reaches \(1\). 3. For \(15\): \(15\rightarrow26\rightarrow40\rightarrow16\rightarrow37\rightarrow58\rightarrow89\rightarrow145\rightarrow42\rightarrow20\rightarrow4\rightarrow16\). The term \(16\) repeats, so this chain also enters a cycle. 4. Only \(13\) is a happy number.

Answer

Only \(13\) is happy: \(13\rightarrow10\rightarrow1\). The chains for \(14\) and \(15\) repeat before reaching \(1\).
Generate shape and number patterns 135
A number pattern starts at \(15{,}000\). After five equal steps forward, it reaches \(17{,}500\). a) Find the size of one step. b) List the five numbers reached by moving forward. c) List the five numbers reached by moving backward from \(15{,}000\) using the same step size.

Hints

- Find the total distance from the starting number to the ending number. - Divide that distance into five equal parts. - Add the step size to move forward and subtract it to move backward.

Solution

1. a) The total change is \(17{,}500-15{,}000=2500\). Divide by the five equal steps: \(2500\div5=500\). 2. b) Add \(500\) repeatedly: \(15{,}500, 16{,}000, 16{,}500, 17{,}000, 17{,}500\). 3. c) Subtract \(500\) repeatedly: \(14{,}500, 14{,}000, 13{,}500, 13{,}000, 12{,}500\).

Answer

a) \(500\) b) \(15{,}500, 16{,}000, 16{,}500, 17{,}000, 17{,}500\) c) \(14{,}500, 14{,}000, 13{,}500, 13{,}000, 12{,}500\)
Generate shape and number patterns 136
Zoe and Ben each build a number wall. Every brick is the sum of the two bricks directly below it. The two walls are shown. a) Find the top brick in Zoe's wall a). b) Find the top brick in Ben's wall b). c) How much greater is Ben's top brick? Explain why the one changed bottom brick creates this exact change at the top.
Figure for problem 531968

Hints

- Complete both walls from the bottom upward. - Compare corresponding bricks in the two walls. - Track every path from the changed bottom brick to the top.

Solution

1. For wall a), the second row is \(170,190,130\). The third row is \(360,320\), so the top is \(680\). 2. For wall b), the second row is \(180,200,130\). The third row is \(380,330\), so the top is \(710\). 3. The difference is \(710-680=30\). The changed bottom brick increases by \(10\) and contributes through three paths to the top, so the top increases by \(3\times10=30\).

Answer

a) \(680\) b) \(710\) c) Ben's top brick is \(30\) greater. The changed bottom brick contributes three times to the top, so the increase is \(3\times10=30\).
Generate shape and number patterns 137
Mia and Jonas compare the two number walls shown. Every brick is the sum of the two bricks directly below it. Jonas claims, “Because the changed bottom brick increased by \(10\), the top brick will also increase by exactly \(10\).” Is Jonas correct? Find the top brick in each wall and explain your answer.
Figure for problem 532002

Hints

- Complete each wall using the stated rule. - Compare the two top bricks only after both walls are complete. - Trace where the changed bottom brick contributes in the next row.

Solution

1. In wall a), the second row is \(270\) and \(330\). The top is \(600\). 2. In wall b), the second row is \(280\) and \(340\). The top is \(620\). 3. The top increases by \(620-600=20\), not \(10\). The changed middle bottom brick contributes to both bricks in the second row, so its change contributes twice to the top.

Answer

No. Wall a) has a top brick of \(600\), and wall b) has a top brick of \(620\). The top increases by \(20\) because the changed middle bottom brick contributes twice to the top.
Generate shape and number patterns 138
Complete both large number walls. Every brick is the sum of the two bricks directly below it.
Figure for problem 532022

Hints

- Start where addition or subtraction gives a missing value directly. - In wall b), subtract the known outside bottom values from \(465\). The remaining amount contains the unknown bottom value twice. - Use a variable or question mark to organize the repeated unknown if helpful.

Solution

1. Wall a): \(205 - 85 = 120\), \(45 + 120 = 165\), \(165 + 205 = 370\), \(770 - 370 = 400\), \(400 - 205 = 195\), and \(195 - 85 = 110\). 2. Wall b): \(205 - 70 = 135\). In the right third-row brick, the two outside bottom values contribute once and the unknown bottom value contributes twice. Thus \(465 - 70 - 95 = 300\), so the unknown is \(300 \div 2 = 150\). Then \(70 + 150 = 220\), \(150 + 95 = 245\), \(205 + 220 = 425\), and \(425 + 465 = 890\).

Answer

a) Bottom row: \(45\), \(120\), \(85\), \(110\); second row: \(165\), \(205\), \(195\); third row: \(370\), \(400\); top: \(770\) b) Bottom row: \(135\), \(70\), \(150\), \(95\); second row: \(205\), \(220\), \(245\); third row: \(425\), \(465\); top: \(890\)
Generate shape and number patterns 139
Complete both number walls. Decide where to begin in each wall.
Figure for problem 535249

Hints

- Add when finding an upper brick from two lower bricks. - Subtract when finding a lower brick from an upper brick and its neighbor. - In wall b), think about how the middle bottom brick contributes to both bricks above it.

Solution

1. Wall a): The right brick in the second row is \(210 + 150 = 360\). The left brick in the second row is \(800 - 360 = 440\). The left bottom brick is \(440 - 210 = 230\). 2. Wall b): The outside bottom bricks contribute \(145 + 145 = 290\) to the top. The middle bottom brick contributes twice, so \(600 - 290 = 310\) and \(310 \div 2 = 155\). The two bricks in the second row are both \(145 + 155 = 300\).

Answer

a) Bottom left: \(230\); second row: \(440\), \(360\) b) Bottom middle: \(155\); second row: \(300\), \(300\)
Generate shape and number patterns 140
This number wall has five rows. Each brick is the sum of the two bricks below it. Find every missing value, and use the symmetry you notice to help you.
Figure for problem 535309

Hints

- Start where a known brick and its neighbor give another brick by subtraction. - Look for places where you can work backward from a known sum. - Compare the left and right sides of the wall as you fill in the unknown bricks. - Check your completed wall by adding upward from the bottom.

Solution

1. The first bottom brick is \(60-40=20\). 2. The middle brick in the third row is \(120\). The two \(40\)s beneath it account for \(80\). The remaining \(40\) comes from two copies of the middle bottom brick, so that brick is \(40\div2=20\). 3. The middle bricks in the second row are \(40+20=60\) and \(20+40=60\). 4. The right brick in the third row is \(240-120=120\). Its right brick below is \(120-60=60\), so the last bottom brick is \(60-40=20\). 5. The bottom row is \(20,40,20,40,20\). Adding upward gives \(60,60,60,60\), then \(120,120,120\), then \(240,240\), and finally \(480\).

Answer

Bottom row: \(20,40,20,40,20\) Second row: \(60,60,60,60\) Third row: \(120,120,120\) Fourth row: \(240,240\) Top: \(480\)
Generate shape and number patterns 141
Complete the five-row number wall. The values are large, but the rule is unchanged: each brick is the sum of the two bricks below it.
Figure for problem 535311

Hints

- Start at the top, where two connected values are already known. - Use the wall's symmetry to check matching values on the left and right. - Keep place values aligned when subtracting three-digit numbers.

Solution

1. The right brick in the fourth row is \(920 - 460 = 460\). 2. The left and right bricks in the third row are each \(460 - 240 = 220\). 3. The left brick in the second row is \(220 - 120 = 100\), so the second bottom brick is \(100 - 45 = 55\). 4. The next brick in the second row is \(240 - 120 = 120\), so the middle bottom brick is \(120 - 55 = 65\). 5. The right brick in the second row is \(220 - 120 = 100\). This gives \(120 - 65 = 55\) for the fourth bottom brick and \(100 - 55 = 45\) for the last one.

Answer

Bottom row: \(45\), \(55\), \(65\), \(55\), \(45\) Second row: \(100\), \(120\), \(120\), \(100\) Third row: \(220\), \(240\), \(220\) Fourth row: \(460\), \(460\) Top: \(920\)
Generate shape and number patterns 142
The top value must become \(800\). Add the same number to each bottom-row value. What will the new bottom row be?
Figure for problem 535326

Hints

- How much must the top brick change? - Try adding \(1\) to each bottom brick and see how much the top changes. - Use the change for \(1\) to work out the needed change in each bottom brick.

Solution

1. The top must increase by \(800-400=400\). 2. If each bottom brick increases by \(1\), each middle brick increases by \(2\) and the top increases by \(4\). Every extra \(1\) added to all bottom bricks therefore increases the top by \(4\). 3. To increase the top by \(400\), add \(400\div4=100\) to each bottom brick. 4. The new bottom row is \(100+100=200\), \(200\), \(200\). Its top is \(400+400=800\).

Answer

The new bottom row is \(200,200,200\).
Generate shape and number patterns 143
Subtract the same amount from each bottom-row value so that the top becomes exactly \(120\). What is the new bottom row?
Figure for problem 535327

Hints

- Compare the original top value with the required top value. - Imagine subtracting \(1\) from each bottom brick. How much would the top change? - Use that change to find the amount to subtract from every bottom brick.

Solution

1. The top must decrease by \(260-120=140\). 2. Subtracting \(1\) from each bottom brick makes each middle brick decrease by \(2\) and the top decrease by \(4\). 3. To decrease the top by \(140\), subtract \(140\div4=35\) from each bottom value. 4. The new bottom row is \(60-35=25\), \(80-35=45\), and \(40-35=5\). Its top is \((25+45)+(45+5)=120\).

Answer

The new bottom row is \(25,45,5\).
Generate shape and number patterns 144
What happens to the top value of a four-brick number wall when the second bottom brick is increased by \(10\)? Compare the two walls and explain why.
Figure for problem 535364

Hints

- Complete wall b) and compare its top with \(500\). - Trace how many times the second bottom brick contributes to the rows above.

Solution

1. Wall a) has top value \(500\). 2. For wall b), the second row is \(160, 110, 150\). 3. The third row is \(160 + 110 = 270\) and \(110 + 150 = 260\). 4. The top is \(270 + 260 = 530\), so it increased by \(530 - 500 = 30\). 5. The second bottom brick contributes to three paths leading to the top. Therefore an increase of \(10\) contributes \(3 \times 10 = 30\) to the top.

Answer

The top value increases by \(30\). The second bottom brick is counted three times in the top value, so increasing it by \(10\) increases the top by \(3 \times 10 = 30\).
Generate shape and number patterns 145
Complete the number wall to the top. Each brick is the sum of the two bricks below it. Use the mirror symmetry in the bottom row.
Figure for problem 535411

Hints

- What does mirror symmetry tell you about the two bricks below the middle \(100\)? - Split a known brick into two equal sums when the wall is symmetric. - Once the bottom row is complete, check upward by addition.

Solution

1. By symmetry, the two bricks directly below the middle \(100\) are equal. Each must be \(100\div2=50\). 2. Each of those bricks includes a known \(20\) from the bottom row, so the middle bottom brick is \(50-20=30\). 3. The bottom row is \(10,20,30,20,10\). Adding adjacent bricks gives \(30,50,50,30\) in the second row. 4. The next rows are \(80,100,80\), then \(180,180\), and the top \(360\).

Answer

Bottom row: \(10,20,30,20,10\) Second row: \(30,50,50,30\) Third row: \(80,100,80\) Fourth row: \(180,180\) Top: \(360\)
Generate shape and number patterns 146
Each brick is the sum of the two bricks below it. The number wall is symmetric. Work backward to complete it.
Figure for problem 535412

Hints

- Subtract from the top where just one brick is missing. - Use the stated symmetry to match bricks on opposite sides. - Use the given middle bricks to check what must lie below them.

Solution

1. The missing fourth-row brick is \(36-18=18\). 2. The outside bricks in the third row must each be \(18-10=8\), so that row is \(8,10,8\). 3. The left \(8\) includes the bottom values \(1\) and \(3\) once each, and the second bottom value twice. Removing \(1+3=4\) leaves \(4\) for two equal copies, so the second bottom value is \(4\div2=2\). 4. By symmetry, the bottom row is \(1,2,3,2,1\). Adding upward gives \(3,5,5,3\), then \(8,10,8\), then \(18,18\), and finally \(36\).

Answer

Bottom row: \(1,2,3,2,1\) Second row: \(3,5,5,3\) Third row: \(8,10,8\) Fourth row: \(18,18\) Top: \(36\)
Generate shape and number patterns 147
Complete the number wall and describe the pattern in the bottom row.
Figure for problem 535415

Hints

- Start with a blank that can be found by subtracting from \(100\). - Watch for repeated values. - Look for mirror symmetry between the left and right sides.

Solution

1. The third bottom brick is \(100 - 50 = 50\). 2. The right brick in the second row is \(50 + 50 = 100\), so the right brick in the third row is \(100 + 100 = 200\). 3. The left brick in the third row is \(400 - 200 = 200\). 4. The left brick in the second row is \(200 - 100 = 100\), so the first bottom brick is \(100 - 50 = 50\). 5. Every bottom brick is \(50\).

Answer

Bottom row: \(50\), \(50\), \(50\), \(50\) Second row: \(100\), \(100\), \(100\) Third row: \(200\), \(200\) Top: \(400\) The bottom row has the constant pattern \(50, 50, 50, 50\).
Generate shape and number patterns 148
Compare the three product walls. In a product wall, each brick is the product of the two bricks directly below it. Find each top value. Which walls have the same result, and why is wall c) different?
Figure for problem 536328

Hints

- Apply the stated product-wall rule from the bottom upward. - Compare the middle bottom value in each wall. - Trace which bottom position affects both second-row bricks.

Solution

1. Wall a) has second row \(2\times3=6\) and \(3\times4=12\), so the top is \(6\times12=72\). 2. Wall b) has second row \(4\times3=12\) and \(3\times2=6\), so the top is \(12\times6=72\). 3. Wall c) has second row \(3\times2=6\) and \(2\times4=8\), so the top is \(6\times8=48\). 4. Walls a) and b) have equal top values. The middle bottom value is used in both second-row products, so it contributes twice. Wall c) puts the smallest value, \(2\), in that influential middle position.

Answer

Walls a) and b) both have top value \(72\). Wall c) has top value \(48\) because its smallest bottom value is in the middle and is used in both products above it.

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