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prep question

by jamesk486 » Sat Apr 21, 2007 8:23 pm
How many multiples of 9 are there between 3^4 and 3^5 (inclusive)?

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Re: prep question

by jayhawk2001 » Sat Apr 21, 2007 8:52 pm
jamesk486 wrote:How many multiples of 9 are there between 3^4 and 3^5 (inclusive)?
Total number of multiples of 9 = (3^5 - 3^4) / 9 + 1 = 18 + 1 = 19

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by Cybermusings » Sun Apr 22, 2007 2:49 am
How many multiples of 9 are there between 3^4 and 3^5 (inclusive)?

3^4 = 3^2*3^2 = 9*9
3^5 = 3^2*3^2*3 = 9*9*3
How many multiples of 9 are between 81 and 243
81/9=9

243/9=27
Hence there are 27-9=18+1 (since both 81 and 243 are inclusive) = 19 multiples

Sorry for the rookie mistake....it's 243/9 and not 729/9...
Last edited by Cybermusings on Wed Apr 25, 2007 6:10 am, edited 1 time in total.

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by jamesk486 » Mon Apr 23, 2007 12:25 am
where did u get the 729?