winfred01

If that's the case, then (Pi X 10^oo)(Previous prime number ,P [Pi-1])(P [Pi-2])(P [Pi-3])(P [Pi-4])....(2) + 1 is another prime number (by default) [just realized it's been mentioned above]

The only way (I know) to solve this problem is by backtracking (with ordinary computers)... unless your friend is using a computer with "special" CPU, I think that's the only way. The Eight queen's problems is a typical demo for backtracking. I will have a go using a matix ( i , j ) and some linear equations y=ax+b...(a = 1,-1) btw, I put Imperial as my insurance so I might be asked to solve this question in the future...um...

Prime numbers are mainly used for encryption. For example, in networking (e.g. Internet) data stream encryption. Large prime number are difficult to be cracked,because calculating them are impractical even for cutting edge CPUs. As I know, governments will pay lots of money for a large prime number . By the way, some of the large prime numbers can be copyrighted, which means using them could be illegal...... (<-- I'm not sure how it works) Correct me if I'm wrong~ By the way, I just discovered this forum today and it's very helpful~