Boys with toys

U.S. researchers have identified the largest known prime number. A team at Central Missouri State University found it last month after programming 700 computers nine years ago. The number found is 9.1 million digits long. It is a Mersenne prime known as M30402457 - that's 2 to the 30,402,457th power, minus 1.

"People ask why we do this," said Dr Steven Boone. "It's like going on a quest. We're looking for something incredibly rare."

Yep, like world peace in our time. Holy Grail Quest, Batman.