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lionelpq
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Guide 1: Chapter 4: Question: 11 (pg. 58, 4th edition)

by lionelpq Tue Jun 29, 2010 5:25 am

The answer to question 11 says "As we learned in Chapter 1, there are (4+1)(1+1)=10 different factors of 2^4*3." What is this formula refered to in Chapter 1 that gets us to 10? I could not find it.

Thanks!
phoenix.rkchr
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Re: Guide 1: Chapter 4: Question: 11 (pg. 58, 4th edition)

by phoenix.rkchr Tue Jun 29, 2010 6:03 am

lionelpq Wrote:The answer to question 11 says "As we learned in Chapter 1, there are (4+1)(1+1)=10 different factors of 2^4*3." What is this formula refered to in Chapter 1 that gets us to 10? I could not find it.

Thanks!


The formula to find the total number of factors of any number N is:

(a+1)(b+1)(c+1)........

where a, b, c, ..... are the powers of prime factors of the number N.

e.g. N = 72
prime factors of 72= 2X2X2X3X3 = 2^3 X 3^2

here a = 3 and b = 2

So number of factors of 72 = (3+1)(2+1) = 12
lionelpq
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Re: Guide 1: Chapter 4: Question: 11 (pg. 58, 4th edition)

by lionelpq Tue Jun 29, 2010 8:48 am

Apreciate it. Thanks
tim
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Re: Guide 1: Chapter 4: Question: 11 (pg. 58, 4th edition)

by tim Thu Jul 08, 2010 1:44 pm

Thanks, Phoenix..
Tim Sanders
Manhattan GMAT Instructor

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