Is y a multiple of 15?

Hi 282552,

DS questions often include a 'test of your thoroughness' - in real simple terms, "do you see more than just the obvious possibilities?"

Here, we're asked if Y is a multiple of 15. This is a YES/NO question. Before you begin working on the two Facts, ask yourself this:

"Do we know ANYTHING about the value of Y?"

Starting off, the answer is NO - there are NO restrictions on the value of Y.... So Y could be positive, negative, zero, a fraction, a square root, some crazy repeating decimal, etc. Most Test Takers only think about the 'obvious' possibilities (positive integers), but you MUST consider the alternatives if you want to make sure that you're choosing the correct answer.

In Fact 1, we're told that Y^2 is a multiple of 15, but that does NOT mean that Y is a multiple of 15. Be thorough with your thinking, look for alternatives, ask yourself if there's anything else that's possible....and you'd be surprised how easy it can be to find those other possibilities.

GMAT assassins aren't born, they're made,
Rich