The way I understand the question is that he wants to have for example many groups of 2, many groups of 3, etc, etc.
There are many possibilities, so let's just look at all the options!
a. 1
- it's technically possible, as 36, 72 and 18 are each divisible by 1 (but I don't think it's a "group"
b. 2
- yes, this is possible! 36, 72 and 18 are each divisible by 2 (they're all even)
c. 3
yes, he can have piles of 3 as 36, 72 and 18 are each divisible by 3
d. 4
NO! they're not divisible by 4
E. 9
yes! it would be 2 piles of nickels, 4 of quarters and 8 of dimes
F. 12
NO! they're not divisible by 12
