Slide 1

Adjusting numbers in a problem in a problem to make to make mental math easier easier

Slide 2

Example Tell the sum of the following group of numbers. 4 + 9 + 7 + 3 + 11 + 1 + 6

Slide 3

How can we easily add these numbers?

Slide 4

Can you find groups of ten? 4 + 9 + 7 + 3 + 11 + 1 + 6 7+3 = 10 6+4 =10 9+1 =10 plus11 Count 10, 20, 30, 40, 41

Slide 5

Can you find groups of ten? 5 + 4 + 12 + 9 + 1 + 6 + 5 9+1 = 10 5+5 =10 6+4 =10 plus12 Count 10, 20, 30, 40, 42

Slide 6

43 +68 40 + 3 60 + 8 43 ~ 40 68 ~ 70 100 + 11 ~ 110

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What number is compatible with 79 ? What number is compatible with 66 ? What number is compatible with 74 ? What number is compatible with 92 ? What number is compatible with 86 ? 80 65 75 90 85

Slide 8

Which number sentence best uses compatible numbers to estimate the difference? 72 43 = 29 A. 60 50 = 10 B. 70 40 = 30 C. 80 40 = 40 D. 75 50 = 25

Slide 9

Which number sentence best uses compatible numbers to estimate the difference? 58 - 39 = 19 A.60 40 = 20C. 68 48 = 20 B.55 40 = 15D. 75 50 = 25

Slide 10

Which number sentence best uses compatible numbers to estimate the difference? 76 39 = 37 A.60 50 = 10C. 80 40 = 40 B.70 40 = 30D. 75 50 = 25

Slide 11

Which number sentence best uses compatible numbers to estimate the sum? 88 + 68 = 156 A. 90 + 70 =160C. 95 + 60 = 155 B. 95 + 65 =160D. 90 + 65 = 155

Slide 12

Which number sentence best uses compatible numbers to estimate the sum? 94 + 61 = 155 A. 90 + 70 =10 C. 95 + 60 = 155 B. 95 + 65 =160D. 90 + 65 = 155

Slide 13

Which number sentence best uses compatible numbers to estimate the difference? 78 43 = 29 A.60 50 = 10C. 80 40 = 40 B.70 40 = 30D. 75 50 = 25