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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
when the number is an even, as in 30's case, from the 1 to that EVEN, the number of even and odd integers are equal.
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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
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Bump for further discussion.

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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
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Prime factors of 30=2*3*5 whose total factors would be (1+1)(1+1)(1+1)=8????

How did you calculate the total factors -- What is this (1+1)(1+1)(1+1)=8????
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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
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shortcut
number of total factors in 30=2^1*3^1*5^1
=(1+1)(1+1)(1+1)
now to get odd and even factors
consider only 1st element in total factor formula e.g(2+1(1+3))
on this example even part is first 2(1+3) and odd factor =1(1+3)

now in our question we can apply the same for all.
even is =1(1+1)(1+1)=4



but be careful when you apply this. e.g. 125=5^3 now in this there is no even factor ,only odd factors.
also consider this for example, 75=5^2*3^1=no even factor
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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: GRE Math Challenge #22- The number of odd positive factors [#permalink]
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