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Re: Quantitative Reasoning [#permalink]
SherpaPrep wrote:
10! means 10x9x8x7x6x5x4x3x2x1. Just getting that out of the way. So if we want to know the maximum value of x, we basically need to count up how many 3s there are in 10!. Every third integer is divisible by 3, so that's 3, 6, and 9. It's a trap to think you're done here. We should also realize that every ninth integer is divisible by 9, and 9 has two 3s as factors. In other words, 9 should count twice. So x = 4, not 3.

Using similar logic, we know that 5 and 10 have factors of 5, so y must be 2. Thus, 2y = 4 and the answer is C.



Are u really sure ANS is C, I don't see "2y", where is it from?
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Re: 10! is divisible [#permalink]
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correct: A
we should write the number 10! into it's simplest form consisting of just prime numbers.
10! = 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = \(2^8 *3^4 * 5^2 * 7\)
10! = \(3^x * 5^y\) so x = 4 and y = 2
so x is bigger than y

Originally posted by Fatemeh on 15 Mar 2018, 15:58.
Last edited by Carcass on 16 Mar 2018, 02:20, edited 1 time in total.
Edited by Carcass
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Re: 10! is divisible [#permalink]
How is the answer C? I am getting A. I have x = 4 and y = 2.
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Re: 10! is divisible [#permalink]
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The sad part of story is that I spent 10 minutes from my valuable time trying to prove me wrong :-D while I was right
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Re: 10! is divisible [#permalink]
Please correct the OA of this question.

Choice A is correct.
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Re: 10! is divisible [#permalink]
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Expert Reply
Done. Thank you guys for your collaboration.

However, next time posts like this one will be closed.

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Re: 10! is divisible [#permalink]
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