Project+Euler

Project Euler

Problem 20

//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!

100! sum of digits of 100! = 648

First, I went to wolframalpha.com and found out what 100! was. I then added all of the digits using wolframalpha. However, I thought there might be an easier way, so I typed "sum of digits of 100!" into the search bar, and it gave me the answer I was looking for.

Solution to Problem 45 Solution to Problem 15