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Easy numbers problem - Divisibility/Prime numbers

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Easy numbers problem - Divisibility/Prime numbers

by neelgandham » Tue Oct 25, 2011 5:36 am
If n is a multiple of 5 and n=(p^2)*q where p and q are prime numbers, which of the following is definitely a multiple of 25

1.p^2
2.q^2
3.p*q^2
4.(p^2)*(q^2)
5.(p^3)*q
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by Anurag@Gurome » Tue Oct 25, 2011 6:00 am
Refer to the post here : https://www.beatthegmat.com/ps-problem-s ... tml#322564
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by shankar.ashwin » Tue Oct 25, 2011 6:27 am
Since n is a multiple of 5, either p or q should be a multiple of 5.
For a multiple of 25, we want 2 5's (or the numbers squared)

Since we aren't sure whether its 'p' or 'q' which is a multiple of 5, we can safely square both of these to obtain a number divisible by 25. Which is precisely option 4
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