From charlesreid1

Sum of Factorial Digits

For this problem, you're asked to sum the digits of 100!. This is a very quick task using a Java library like BigInteger - the Go programming language also has the facilities built-in to handle numbers as large as 800!.

To do this in Java, you can use the BigInteger class, convert it to a String, and then turn the characters in the string into digits one at a time to sum them up.