#20: Factorial digit sum | Ben Cunningham

# #20: Factorial digit sum

Problem by Project Euler · on June 21, 2002

$n!$ means $n \times (n − 1) \times \ldots \times 3 \times 2 \times 1$

For example, $10! = 10 \times 9 \times \ldots \times 3 \times 2 \times 1 = 3628800$, 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 $100!$

# Python

import functools
import operator
import math

def v_sum(x):
if len(x) < 1:
return 0

## 648