This should work,
find f(6)**(10 raised to 7)
On Mon, 14 Sep 2009 18:36:57 +0530, Shashwat Anand
<anand.shash...@gmail.com> wrote:
How do we calculate last 5-digits of 10**12 ignoring trailing zeros. The
code i wrote works good until 10**8 and after that take ages.
The source of problem is Project Euler :
http://projecteuler.net/index.php?section=problems&id=160
The code is pasted here : http://paste.pocoo.org/show/139745/
1 '''
2 For any N, let f(N) be the last five digits before the trailing
zeroes
in N!.
3 For example,
4
5 9! = 362880 so f(9)=36288
6 10! = 3628800 so f(10)=36288
7 20! = 2432902008176640000 so f(20)=17664
8
9 Find f(1,000,000,000,000)
10 '''
11 def f(n):
12 fac = 1
13 i = 1
14 #for i in range(1, n+1):
15 while i < n + 1:
16 fac = int(str(fac * i).strip('0')) % 100000
17 i += 1
18 return fac
19
20 print f(1000000000000)
PS. hope posting algorithmic doubts will not be considered spamming :)
--
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