No . of factors or divisors

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No . of factors or divisors

by vikram4689 » Wed Jun 29, 2011 6:56 am
Hey i saw a MGMAT ques that asks to find No. of factor in 36*36. Ans given is 25 BUT i think that is the answer to No. of divisors. And no. of factors = 2*No of divisor as factors are +ve as well as -ve.

Also this is the reason we say that sum of factors of any number is 0.

Experts please comment.
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by Frankenstein » Wed Jun 29, 2011 7:08 am
Hi,
Whenever we talk about factors, we should consider only positive ones(at least on GMAT). So, number of factors being 25 is correct.
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by Ashley@VeritasPrep » Wed Jun 29, 2011 10:50 am
Confirming. "Factor" and "divisor" are used totally interchangeably with each other, but you only need to think about the positive ones for these purposes.
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by vikram4689 » Wed Jun 29, 2011 7:39 pm
Thanks Ashley & Frankenstein.
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by amit2k9 » Thu Jun 30, 2011 3:19 am
number of factors
36 = 2^2 * 3^2

36* 36 = 2^4 * 3*4

thus (4+1) * (4+1) = 25 is the number of factors here.
factors are positive in GMAT.
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