## Re: [2IIM CAT Prep]

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• ..the ans is 8.. error in 1st line in previous mail ... -- regards, rahmath
Message 1 of 1 , Aug 2, 2011
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..the ans is 8.. error in 1st line in previous mail

On Tue, Aug 2, 2011 at 7:41 PM, RAHAMATHULLAH ELYAS wrote:
..the ans is not  2.. its '4'
..the way u ppl proceeded is right, but u forgot dat between 21 - 30 der are two 5's ..i.e. 25=5*5 ..
one of the 5 multiplied wid 2 nd other wid 4..which gives two zeros..
der fore it will be 8*8*2..whose unit place will be 8

On Fri, Jul 22, 2011 at 1:05 PM, pradeep barola wrote:

I am also getting 2 as answer:

1*2*3*4*5*6*7*8*9= it has 8 as the last non zero digit

and doing this three times 8*8*8 has 2 as last non-zero digit

On Tue, Jun 21, 2011 at 3:32 PM, deepak narayanan wrote:

Q1. There are 7 zeroes in the end of 30! (factorial 30). Which digit precedes these zeroes?

a.8
b.3
c.4
d.7

I could get the number as 2 .

Taking the first 10 numbers (10!) will end in

10! = 1*2*3*4*5*6*7*8*9*10

Eliminating: 1, 2,5 as they contribute only to the zeros we get

3*4*6*7*8*9 = 8. 10! = 32...800.So,8 precedes the zeroes.

Working on the same fashion for 30!,I'm getting 2 as the number that is not listed in the options.

Anything wrong?

-Deepak.

--

--
regards,
rahmath

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--
regards,
rahmath

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