130 likes | 399 Views
COMPATIBLE NUMBERS. Adjusting numbers in a problem to make mental math easier. Example Tell the sum of the following group of numbers. 4 + 9 + 7 + 3 + 11 + 1 + 6. 4 + 9 + 7 + 3 + 11 + 1 + 6. How can we easily add these numbers?. Can you find groups of ten?
E N D
COMPATIBLE NUMBERS Adjusting numbers in a problem to make mental math easier
Example Tell the sum of the following group of numbers. 4 + 9 + 7 + 3 + 11 + 1 + 6
4 + 9 + 7 + 3 + 11 + 1 + 6 How can we easily add these numbers?
Can you find groups of ten? 4 + 9 + 7 + 3 + 11 + 1 + 6 7+3 = 10 6+4 = 10 9+1 = 10 plus 11 Count 10, 20, 30, 40, 41
Can you find groups of ten? 5 + 4 + 12 + 9 + 1 + 6 + 5 9+1 = 10 5+5 = 10 6+4 = 10 plus 12 Count 10, 20, 30, 40, 42
43 +68 40 + 3 60 + 8 43 ~ 40 68 ~ 70 100 + 11 ~ 110 Exact Answer Estimate
80 What number is compatible with 79? 65 What number is compatible with 66? 75 What number is compatible with 74? 90 What number is compatible with 92? 85 What number is compatible with 86?
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
Which number sentence best uses compatible numbers to estimate the difference? • 58 - 39 = 19 • 60 – 40 = 20 C. 68 – 48 = 20 • 55 – 40 = 15 D. 75 – 50 = 25
COMPATIBLE NUMBERS • Which number sentence best uses compatible numbers to estimate the difference? • 76 –39 = 37 • 60 – 50 = 10 C. 80 – 40 = 40 • 70 – 40 = 30 D. 75 – 50 = 25
Which number sentence best uses compatible numbers to estimate the sum? • 88 + 68 = 156 • 90 + 70 =160 C. 95 + 60 = 155 • B. 95 + 65 =160 D. 90 + 65 = 155
Which number sentence best uses compatible numbers to estimate the sum? • 94 + 61 = 155 • 90 + 70 =10 C. 95 + 60 = 155 • B. 95 + 65 =160 D. 90 + 65 = 155
COMPATIBLE NUMBERS • Which number sentence best uses compatible numbers to estimate the difference? • 78 – 43 = 29 • 60 – 50 = 10 C. 80 – 40 = 40 • 70 – 40 = 30 D. 75 – 50 = 25