A pair of Japanese and US computer whizzes claim to have calculated pi to five trillion decimal places -- a number which if verified eclipses the previous record set by a French software engineer.

"We believe our achievement sets a new record," Japanese system engineer Shigeru Kondo said, adding that the French man's calculation to nearly 2.7 trillion places was believed to be the previous record.

The 54-year-old from central Japan, teamed up with Alexander Yee, a US computer science student, to set about calculating the constant that has fascinated mathematicians for millennia.

Pi, the ratio of a circle's circumference to its diameter, starts with 3.14159 in a string whose digits are believed to never repeat or end.

"Alexander provided software and I was in charge of hardware. We couldn't have achieved the results without either of us," Kondo said, adding that the two men worked together while communicating by email.

It took 90 days to calculate pi at Kondo's home using a desktop computer with 20 external hard disks. It ran on the operating system Windows Server 2008R2 and used powerful Intel microprocessors. Verification took 64 hours.

Kondo built the computer by himself, procuring parts from local electronics shops and via the Internet. "I don't really want to say how much it cost me as my family may hear it... it's about 18,000 dollars," he told AFP by telephone.

It was midnight in Japan when the computer reached five trillion decimal places. "I was alone in the room at the moment... I know this is nothing but self satisfaction," he said.

His mother and wife who live with him were sleeping at that time and later showed "no particular feelings" despite his sense of achievement, he said.

Earlier this year Fabrice Bellard of France said he had used an inexpensive desktop computer -- and not a supercomputer like those used in past records -- to calculate pi to nearly 2.7 trillion decimal places.

That was around 123 billion digits more than the previous record set last August by Japanese professor Daisuke Takahashi.

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(c) 2010 AFP