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Number of co-primes to N, that are less than N

Expert replies
Source: — Problem Solving |

by parveen110 » Sat Feb 08, 2014 6:48 am
Even i was wondering this. I think it has something to do with progressions or combinatorics. Not sure. Experts please weigh in if there is a simple logic involved. Thanks!
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by [email protected] » Sun Feb 09, 2014 11:23 am
Hi parveen110,

Is there a GMAT question attached to this concept that you'd like to review?

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by Brent@GMATPrepNow » Sun Feb 09, 2014 3:49 pm
Rest assured that the concept of "coprime integers" (and this suspicious formula) is not required knowledge for the GMAT. Yes, it's conceivable that a GMAT question might test a certain aspect of coprimes, but if it did, the question would include a definition of "coprime."

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