Tinyurl-style unique code: potential algorithm to prevent collisions

Question

I have a system that requires a unique 6-digit code to represent an object, and I\'m trying to think of a good algorithm for generating them. Here are the pre-reqs:

Answer 1

My math is a bit rusty, but I think you just need to ensure that the GCF of N and 64 million is 1. I'd go with a prime number (that doesn't divide evenly into 64 million) just in case though.