# Clue to puzzle #19: 100 Factorial

19. How many consecutive zeros are there at the end of 100! (100 factorial). How would your solution change if the problem were in base 5? How about in Binary???

The trick to this is working out what, when multiplied together, will result in the creation of a zero. For example if i were to ask how many zeros were on the end of 3 x 7 x 9 x 8 you know there are no zeros. But what about 3 x 7 x 9 x 8 x 5 ?

The same technique can be applied in all bases.

Where next?

Questions Answer

© Nigel Coldwell 2004 - – The

**questions**on this site may be reproduced without further permission, I do not claim copyright over them. The

**answers**are mine and may not be reproduced without my expressed prior consent. Please inquire using the link at the top of the page. Secure version of this page.