# Problem 20 - Factorial digit sum
# 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!
from math import factorial as f
print(sum(int(c) for c in str(f(100))))

Create 20.py