###### September 28, 2008

# Mathematicians Discover 13-Million Digit Prime Number

A team of mathematicians at University of California Los Angeles (UCLA) has discovered the world's largest known prime number.

The 13-million-digit Mersenne prime number, discovered last month with the help of 75 networked Windows XP computers, has stirred widespread interest and represents the achievement of long-sought milestone.

"We're delighted," UCLA's Edson Smith, the leader of the effort, told the AP.

"Now we're looking for the next one, despite the odds."

Independent systems have verified the results using different algorithms.

Prime numbers are those that are only divisible by themselves and the number one. Examples include the numbers three, seven and 11. Mersenne primes are expressed as "2P-1", or two to the power "P" minus one, where P is a prime number. For the new number discovered at UCLA, the 46th such Mersenne prime, P is equal to 43,112,609.

Mersenne primes are named after 17th century French mathematician Marin Mersenne, who discovered them.

Thousands of scientists worldwide have taken part in the Great Internet Mersenne Prime Search (GIMPS), a collaborative system in which underused computing power is tapped to conduct the necessary calculations to find and verify Mersenne prime numbers.

The Electronic Frontier Foundation (EFF), a nonprofit organization that promotes digital rights on the Internet, is awarding a $100,000 prize for the discovery of the first Mersenne prime number containing more than 10 million digits. The foundation established the prime number contest to encourage co-operative computing on the Internet. The prize could be awarded some time next year, when the new prime is published.

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