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PS Number Properties

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PS Number Properties

by abhi75 » Thu Apr 24, 2008 12:47 pm
If n is the product of the integers from1 to 20 inclusive, what is the greatest integer k for which 2k is a factor of n?
A. 10
B. 12
C. 15
D. 18
E. 20

Can someone please explain this. I will post the OA.
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by gmatguy16 » Thu Apr 24, 2008 3:41 pm
is the question 2 k or 2 ^ k (2 raised to k)
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by xilef » Thu Apr 24, 2008 4:35 pm
I'll assume the question asks 2^k, because 2*20 is definitely not the greatest factor of n.

so basically n=1*2*3*2*2...

in order for 2^k to be a factor of n, all the 2s in the denominator have to be present in the numerator. n has a total of 18 2s.

Answer D
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by abhi75 » Fri Apr 25, 2008 4:08 am
Sorry for the confusion. It is 2^k. OA is D.

Thanks xilef.
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