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Prime numbers and division

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Source: — Data Sufficiency |
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by theCodeToGMAT » Tue Dec 10, 2013 10:07 am
n = 5 x _
n = p^2 * q = p*p*q
5x_=p*p*q

that means either p = 5 x _
or, q = 5 x _

So, to be sure of multiple of 25.. we need square of both

[spoiler]{D}[/spoiler] p^2*q^2 satisfies
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by kobel51 » Wed Dec 11, 2013 8:25 am
A multiple of 25 has 5 twice. since n is a multiple of 5, either p or q is 5. p^2 * q^2 must have 5 twice, so that must be a multiple of 25
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