Determining a multiple of a power of 2.

Question

I am thinking about this question which I believe is a possible GRE question.

"Which of the following numbers is exactly divisible by 32?

A) $1.9 \times 10^5 $

B) $1.9 \times 10^6$

C) $1.9 \times 10^4$ "

In this case I believe that if x is a non-zero integer then $x \times 10 ^n$ is exactly divisible by $2^n$.

My question is this: Is this a good question for GRE students?

Answer 1

HINT:

Write it as

$19×10^4 , 19×10^5 , 19×10^3$

Since 19 is not divisible by 32, the power of 10 must be.

Use $32=2^5$ and $10=2×5$