One afternoon as the cows were chewing their cud, Bessie said, "Let's have a contest to see who is the smartest cow. Here's the contest: we will choose a positive number N (no larger than 2,000,000) and whoever computes the rightmost non-zero digit of N factorial will be crowned the smartest cow."
The other cows demurred, however, mooing, "We did that last year."
"Oh," said Bessie, "but there's a catch. We're not necessarily going to use base 10. I know my hooves don't have that many digits! We'll just specify a positive number base B from 2 through 30."
Write a program to help the cows judge their intelligence contest.