From the Project Euler

*Problem 20:*

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!*

**checked**