If k/mn, where k, m and n are positive integers, is a fracti

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[GMAT math practice question]

If k/mn, where k, m and n are positive integers, is a fraction in its lowest terms, is k/mn a terminating decimal?

1) 1/m is a terminating decimal
2) 1/n is a terminating decimal

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by [email protected] Revolution » Wed May 15, 2019 11:26 pm

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=>

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question.

In order for k/mn to a terminating decimal, mn must have no prime factors other than 2 and 5. This implies that neither m nor n have prime factors other than 2 and 5. Thus, we need both conditions 1) & 2) together.

Therefore, C is the answer.
Answer: C