Question

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

Answer 1

a) (2+8)+9

b) (3+7)+5+4

c) (4+16)+2

d) (31+9)+4

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