Question

For each collection of three groups of addition problems below, choose one strategy from the following list that may be useful in solving each collection of three problems. (“One more than and two more than”, “doubles”, “combinations of 10”, “making 10”, “using 5 as an anchor”, “near-doubles”).

a. 5+2, 1+6, 2+7

b. 6+8, 5+4, 6+5

c. 7+4, 7+9, 9+3

Answer 1

(a) 5+2, 1+6, 2+7

For the above group of addition problems, the "one more than and two more than” strategy will be useful.

This strategy is used when adding 1 or 2 to a given number and the addition is done by counting on. Here, 5+2 is evaluated by counting on from 5 and we get 7. 1+6 is evaluated by counting on from 6 and we get 7. 2+7 is evaluated by counting on from 7 and we get 9.

(b) 6+8, 5+4, 6+5

For the above group of addition problems, the "near-doubles” strategy will be useful.

This strategy is used when a known double is used to evaluate the addition. For example,

6+8=6+6+2=12+2=14

We use the known fact that the double of 6 is 12.

Similarly,

5+4=1+4+4=1+8=9

6+5=1+5+5=1+10=11

(c) 7+4, 7+9, 9+3

For the above group of addition problems, the "making 10” strategy will be useful.

This strategy is used when we break one number and try to add two numbers to make a 10. For example,

7+4=7+3+1=10+1=11

We break 4 into 3+1 and add 7 and 1 to make a 10.

Similarly,

7+9=6+1+9=6+10=16

9+3=9+1+2=10+2=12