Phan -

"You give me the largest known prime number. I can always find a bigger one. " -- this is what the posters are telling you.

This is what Cameron et al did:

You wanna do this, too? go to the Mersenne prime org site and download the free software. You need a 1GHz PC or so ans about 10-12 weeks of free time on the PC.

http://www.mersenne.org/prime.htm