# Project Euler - Problem 20

Aashu Aggarwal

Greenhorn

Posts: 4

posted 4 years ago

Problem statement -

I am trying to solve it but 100! is big even for long. I thought i can try to break the factorial in parts and then solve it but still in end i have to multiply all the results which overshoot the long.

Looking for some guidance.

Thanks,

Aashu

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!

I am trying to solve it but 100! is big even for long. I thought i can try to break the factorial in parts and then solve it but still in end i have to multiply all the results which overshoot the long.

Looking for some guidance.

Thanks,

Aashu

posted 4 years ago

- 2

Check the java API for something that might let you work with a Big Integer...

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors