Hexadecimal interview

[admin]

This puzzle is a variant of the typical job interview question what are the number of trailing zeros of a factorial ?

This puzzle requires you to write a program that computes the number of trailing zeros of factorial(v), when this number is represented in hexadecimal.

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[Prashant Verma]

can anyone explain to me how is the op for 15 is 2 . should it not be 3 ?
and also for for 18 3 instead of 4.
pls help.

[David Berthelot]

Well, here's a little python code that shows why:

Code: Select all

Python 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)] on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>> fact = lambda x:fact(x-1)*x if x > 0 else 1
>>> print hex(fact(15))
0x13077775800L
>>> print hex(fact(18))
0x16beecca730000L