stonecold wrote:

Ramon wants to cut a rectangular board into identical square pieces. If the board is 18 inches by 30 inches, what is the least number of square pieces he can cut without wasting any of the board?

(A) 4

(B) 6

(C) 9

(D) 12

(E) 15

Source -> Manhattan

If we aren't wasting any wood, the length and width must be divisible by one side of the square

So, this question is a clever way of asking us what the greatest common divisor (GCD) of 18 and 30

The GCD of 18 and 30 is 6, so if we cut squares that are 6 x 6, then we won't waste any wood.

We get something like this:

So, we can cut 15 squares.

Answer: E

Cheers,

Brent

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