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Pls help to explain this prob

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Jason.tuyj
 Post subject: Pls help to explain this prob
 Post Posted: Sat Sep 03, 2011 7:46 am 
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If n is the greatest positive integer for which 2^n is a factor of 10!, then n =
A. 2 B. 4 C. 6 D. 8 E. 10
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mithunsam
 Post subject: Re: Pls help to explain this prob
 Post Posted: Sat Sep 03, 2011 3:20 pm 
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10! = 1*2*3*4*5*6*7*8*9*10 = 1*2*3*(2^2)*5*(2*3)*7*(2^3)*9*(2*5) = 1*3*5*3*7*9*5*(2^8) [grouping all 2s together]

10! has eight 2s in it. Therefore n=8 is the answer.
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tim
 Post subject: Re: Pls help to explain this prob
 Post Posted: Tue Oct 04, 2011 12:32 am 
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Thanks mithunsam!

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Tim Sanders
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