Saraforgre wrote:

Please help me with this GRE math question.

if the remainder is 27 when an integer is divided by 36, then the integer must be a multiple of which of the following integer?

A. 8

B. 7

C. 8

D. 9

E. 10

I know the answer is D. 9. But I do not know why. Please help me!

Since the problem states that the solution MUST be divisible by one of the answer choices, we know that it doesn't matter what value of n we use as long as there is a remainder of 27 when it's divided by 36. In that case, why not use the easiest test value of all, n=27? The only choice 27 is divisible by is 9 so the answer is D.

Alternatively, choose any multiple of 36, add 27 and see what it's divisible by.