Office Riddle 05-02-11

May 2nd, 2011

I pose weekly problems to my colleagues ranging from simple algorithmic problems to deep riddles.

I have decided that this week will be a fairly well-known math problem that it is unlikely most of them have solved.

How many trailing zeros does the number "100!" have?

Keywords:
riddle,puzzle

6 replies

On May 2nd, 2011 18:31 Mike wrote
three, 100 x 11 x 10 x 1 = 11000
On May 3rd, 2011 00:09 Daniel wrote
100! = 100*99*98*97 ... *3*2*1 so... no.
On May 3rd, 2011 03:48 DaveDuncan wrote
Oh, you meant 100 in base 10??
On May 3rd, 2011 03:54 DaveDuncan wrote
24 (from Dave, Jason, and Jerry)in the OTP Bachelor Pad.
On May 3rd, 2011 03:57 DaveDuncan wrote
2 from 100 1 each from 10-90 (by tens) That's 11. 10 more from each pair of numbers ending in the digits 2 and 5 That's 21 Jerry figure out there are three more, from 4, 6, and 8 times 25, 50, and 75 Total of 24.
On May 3rd, 2011 15:28 Daniel wrote
I meant 100 factorial. So does your algorithm extend to answer if I ask you how many zeros are in 10000! (10,000 factorial)
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