n! means n × (n − 1) × ... × 3 × 2 × 1

For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800, and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.

Find the sum of the digits in the number 100!



In [1]:

    
import operator



In [2]:

    
def foo(n):
    return reduce((lambda x, y: int(x) + int(y)), str(reduce(operator.mul, range(1, 100 + 1))))



In [3]:

    
n = 100
%timeit foo(n)
foo(n)









    



1000 loops, best of 3: 233 us per loop






    Out[3]:





648