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## Prime Numbers.

From K2C Inspired by "The Times" Wednesday's supplement
"Interface"11/9/96 re Prime Numbers.

Amateur mathematicians across the world are joining
forces to beat the professionals in the numbers game.
Last week the pros, Paul Gage and David Slowinski of The
Cray Research Unit, discovered the biggest Prime Number to date -
comprising of 378,632 digits!
Using a Cray T94 super computer - one of the most
powerful computers in existence - they took only 6 hours to check
that the number could not be written as the product of two
smaller numbers.
Now they are being challenged by programmer George
Woltman in Florida, armed only with a Pentium PC, access to
Internet and a little help from his friends.
Woltman believes that the combined forces of hundreds of
PCs co-ordinated via the Internet can claim the prize for the
next largest Prime.
Since January he has co-ordinated via his Web site a
growing army of PCs which now number 430.
"There is no way a lone computer can compete with
supercomputers, but if we work as a team we can accomplish a
great deal", he says.
To calculate Gage and Slowinski's Prime Number, you
should multiply 2 by itself 1,257,787 times and subtract 1. You
can see the result at Web site:-

http://reality.sgi.com/csp/iocc/noll/prime/prime.html

- but be warned, it would take 12 pages of "The Times" to print
it out!
Finding such huge numbers may sound like an obscure
mathematical curiosity, but Silicon Graphics' Cray Research Unit
regards it as a rigorous way to test the performance of its
computers before they are sent out to deal with real world
problems.
"This acts as a real torture test for a computer" says
Slowinski, "There aren't many practical uses for Formula One race
cars but some of the things engineers do to make these cars
perform better eventually find their way into the cars that you
and I drive."
Anyone who would like to test their own computer by
joining Woltman's call to go forth and multiply in search of an
even bigger Prime Number should visit his Web site at:-

http://ourworld.compuserve.com/homepages/justforfun/prime.html

The author of this report is Dr. Marcus de Sautoy who is a Royal
Society University Research Fellow at the Department of Pure
Mathematics in Cambridge.