## Math Basics## More About Numbers |

## What is GIMPS? |

GIMPS stands for the Great Internet Mersenne Prime Search, a program started in January 1996 to discover new world-record-sized Mersenne prime numbers. It harnesses the power of the Internet—and thousands of small computers belonging to public and private concerns.

This worldwide volunteer computing project made history in 2009, when the Electronic Frontier Foundation awarded GIMPS a $100,000 Cooperative Computing Award. The award was for the August 23, 2008 discovery of the 47th known Mersenne prime (M47). This huge 12,978,189 digit number was found on a University of California (Los Angeles) computer in the GIMPS PrimeNet network. So far, the GIMPS project has discovered thirteen Mersenne primes, with the latest—the 47th found by Odd Magnar Strindmo from Melhus, Norway—on April 12, 2009.

Not only do the volunteers with GIMPS search for the elusive record Mersenne primes, but it also is used to verify others found. For example, by July 2010, seven years after the 40th known Mersenne prime was discovered, GIMPS members double-checked all the smaller Mersenne primes, and found no other primes. Thus, the “40th known Mersenne prime” became the “40th Mersenne prime.”

The collaboration is still going on and, in fact, there are other awards for finding the various prime numbers. There are still two Cooperative Computing Awards up for grabs: the EFF award of $150,000 to the first person or group who discovered a prime with at least 100 million digits. Another is the CCA for discovering a prime with at least a billion digits, a prize worth $250,000.

GIMPS uses around 8 MB of memory and 10 MB of disk space per personal computer, and the computer should be on most of the time. If you decide to join the GIMPS group, be patient—a test can take a while to complete. To find out how you can get involved with GIMPS, get on your computer, log on to the Internet, and type http://www.mersenne.org/prime.htm into your browser. You’ll find directions for downloading the correct software right on the GIMPS site.