Factorial digit sum

Computer Science Level 3

Find the sum of the digits in the number 2015 ! 2015! .


The answer is 23517.

Khang Nguyen Thanh by Khang Nguyen Thanh , 27, Vietnam

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4 solutions

Kartik Sharma
Oct 8, 2015

Well, the following program is really too straight-forward but it worked in 2 s on my Python IDLE. 

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>>> import math
>>> s = 0
>>> for i in str(math.factorial(2015)):
    s +=int(i)
>>> print s
23517

2 Helpful 0 Interesting 0 Brilliant 0 Confused

1 line of code def sumoffactorialdigits(n): print (sum(map(int,str( functools.reduce(operator.mul, range(1,n+1))))))

Hasmik Garyaka - 3 years, 9 months ago
Arulx Z
Nov 3, 2015

It's easy to directly compute the answer 

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>>> import math
>>> sum(int(x) for x in str(math.factorial(2015)))
23517

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Vijay Kumar
Jan 26, 2016

print reduce(lambda x,y : x+y , [0]+map(int,list(str(fact[2015]))))

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Ramiel To-ong
Dec 16, 2015

nice problem

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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