GMAT Prep Test 1 PS 1

450 can be expanded to 3*3*5*5*2

We're told that 450y is n^3, and that both n and y are integers. So, we must be able to take a cube root of 450y and get an integer.

450 itself has two 3's, two 5's and one 2. That means y must give an extra 3, an extra 5, and two more 2's in order for 450y to be a perfect cube root.

So at minimum, y must be 3 x 5 x 2^2.

I only?

450 = 3^2 * 5^2 * 2...So if this has to be a perfect cube it shld be multiplied by 3*5*2^2 = y...Now I hope u shld be able to get the ans.....It is B