smallest prime

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smallest prime

by cmr209 » Mon Aug 17, 2009 10:25 pm

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by prindaroy » Tue Aug 18, 2009 12:03 pm
The answer E. this question has been asked before but I don't where the thread is but anyways;

h(100) = 2*4*6*................*100

= 2(1*2*3*4................*50)

so for a divisor of h(100) + 1, to happen, it would have to be greater than 50 or in this case 40.

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by winnerhere » Tue Aug 18, 2009 11:47 pm
prindaroy wrote:The answer E. this question has been asked before but I don't where the thread is but anyways;

h(100) = 2*4*6*................*100

= 2(1*2*3*4................*50)

so for a divisor of h(100) + 1, to happen, it would have to be greater than 50 or in this case 40.
could u please explain the last line please. :)

and in the previous step its 2^50...u cant take just 2 out as its not summation but multiplication inside the bracket.

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by prindaroy » Tue Aug 18, 2009 11:51 pm
Okay,

so ever number from 1 to 50 will divide h(100) right? But not one of those numbers will divide h(100)+1, because they already divide h(100). So the smallest number that will do so, has to be greater than 50. In the choices given, greater than 40 is the only choice that reflects our solution. So E is the answer

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by tohellandback » Wed Aug 19, 2009 12:00 am
this question has been discussed a zillion times..
Please go here

https://www.beatthegmat.com/gmat-prep-q-t14339.html
The powers of two are bloody impolite!!

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by winnerhere » Wed Aug 19, 2009 12:04 am
prindaroy wrote:Okay,

so ever number from 1 to 50 will divide h(100) right? But not one of those numbers will divide h(100)+1, because they already divide h(100). So the smallest number that will do so, has to be greater than 50. In the choices given, greater than 40 is the only choice that reflects our solution. So E is the answer
great understood :)