## Factorial trailing digits

### Problem 160

Published on Friday, 7th September 2007, 02:00 pm; Solved by 1994; Difficulty rating: 60%For any N, let f(N) be the last five digits before the trailing zeroes in N!.

For example,

9! = 362880 so f(9)=36288

10! = 3628800 so f(10)=36288

20! = 2432902008176640000 so f(20)=17664

Find f(1,000,000,000,000)