6. Regroup the numbers in the following problems, putting the numbers that add up to 10 or a multiple of 10 in parentheses.

a. 2 + 9 + 8

b. 3 + 5 + 4 + 7

c. 4 + 2 + 16

d. 31 + 4 + 9

a) (2+8) + 9

b) (3+7) + 5+4

c) (4+16) + 2

d) (31+9) + 4

Step-by-step explanation:

a) 2+9+8

2 and 8 add up to 10, so we regroup them in parentheses

(2+8) + 9

b) 3 + 5 + 4 + 7

3 and 7 add up to 10, so we regroup them in parentheses

(3+7) + 5+4

c) 4 + 2 + 16

4 and 16 add up to 20 which is a multiple of 10, so we regroup them in parentheses

(4+16) + 2

d) 31 + 4 + 9

31 and 9 add up to 40 which is a multiple of 10, so we regroup them in parentheses

(31+9) + 4