Trailing zeros of 100!
Vlastimil Brom
vlastimil.brom at gmail.com
Sat Jan 2 07:44:26 EST 2016
2016-01-02 12:49 GMT+01:00 <katye2007 at gmail.com>:
> Hi, newbie here!
> I'm trying to write a python program to find how many trailing zeros are in 100! (factorial of 100).
> I used factorial from the math module, but my efforts to continue failed. Please help.
>
> Thank you,
> Yehuda
> --
> https://mail.python.org/mailman/listinfo/python-list
Hi,
rather an illustration of the available tools in python, than a
(submittable) solution:
>>> import re, math
>>> len(re.search(r"0*$", str(math.factorial(100))).group())
24
[or the same code on more lines with some indentation - if it is
preserved via e-mail]
>>> len(
... re.search(
... r"0*$",
... str(
... math.factorial(100)
... )
... ).group()
... )
24
>>>
I.e. You need the length of the string resulting as the match of the
regular expression search for a pattern representing zero or more "0"
at the end of the input text, which is the string version of 100!
Of course, there are other ways to get this result :-)
regards,
vbr
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