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100 factorial

here's  a new problem you might find fun.  the question is:  how many zeroes appear at the end of the rather large number 100!

that's 100 factorial, not yelling the number 100. :)

I recently used your site for studying for a msft interview.  Although I didn't get any questions from your site that I hadn't already heard before, it did help to see so many logic problems.  thanks!  oh, i got the job by the way. :)

Jesse Hersch
Friday, March 22, 2002

and if you find that one too easy, why not find how many zero digits *total* are in 100!

Jesse Hersch
Friday, March 22, 2002

sorry for being redundant.  i just found that this question is already on the site!  oops. 

http://www.techinterview.org/Puzzles/fog0000000149.html

Jesse Hersch
Friday, March 22, 2002

I think the answer to the trailing 0s problem should be 21.

for      for    for
10s    5s    100
-------------------
10  + 10 +  1

why additional 3 ?? I couldn't understand?

because I think any even number not ending with 0 if multiplied with 5 gives some number ending with 0. If multiplied by 5 again the number of trailing 0s wont increase.

may be my whole understanding of the problem itself is wrong.

comments ...

Govind Jajoo
Friday, March 22, 2002

I take back my posting. I got it now.

thanks for ur patience.

Govind Jajoo
Friday, March 22, 2002

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