Problem 20

Solution to Problem 20. Written in Python.

Problem: n! means n x (n - 1) x … x 3 x 2 x 1. For example, 10! = 10 x 9 x … x 3 x 2 x 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!

def fact(n):
    if (n == 1):
        return 1

    return n * fact(n - 1)

x = fact(100)
sum_num = 0
for i in str(x):
    sum_num += int(i)

print str(sum_num)