Lesson: Conversions with Fractions and Decimals

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Can you please help me with an explanation of the answer to the following question:

If r and s are positive integers, is r/s a terminating decimal?
Statement 1: r is a factor of 100
Statement 2: s is a factor of 500
gmat-admin's picture

You bet!

I have provided a full solution here (2nd post): http://www.beatthegmat.com/if-r-and-s-are-positive-integers-is-r-s-a-ter...


Hi Brent
I couldn't understand where are thos r=1, s=4 or r=1 s=3 coming from. Couldn't get the relation, can you help about that?
gmat-admin's picture

Link: http://www.beatthegmat.com/if-r-and-s-are-positive-integers-is-r-s-a-ter...

Once I decided to test some values, I needed to come up with values that satisfy the given conditions.

For statement 1, this means that r must be a factor (aka divisor) of 100. For the s-value, there are no conditions in statement 1, but the given information tells us that s is a positive integer.

NOTE: When we test value like this, our goal is to determine whether there are certain values that will provide different answers to the target question (which means the statement is not sufficient.

So, I recognized that the values r = 1 and s = 4 yield a terminating decimal, and the values r = 1 and s = 3 yield a NON-terminating decimal.

For more on testing values, see this article: http://www.gmatprepnow.com/articles/data-sufficiency-when-plug-values


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