In the UK thats not what they should teach. They are suppposed to teach primes have two distinct factors, 1 and the prime. As for 1 these are both the same number its not prime. On 2 Apr 2012 07:34, "Eric Smith" <eric at brouhaha.com> wrote: Derrik Walker wrote: I wonder how much progress Bill Gates has made on the mathematical problem he pointed out in his book, of factoring very large prime numbers.