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Japanese man calculates pi to 10 trillion digits

Working with a U.S. grad student, a man in Nagano, Japan, has calculated the value of pi to a record 10 trillion digits on a hacked-together home PC.

The 10-trillion pi output screen. The times don't reflect actual computation.
Screenshot by Tim Hornyak/CNET from Numberworld.org

TOKYO--Who knew that "1989" was near the 10-trillionth digit in the value of pi? No one until now.

Two years ago, I speculated that a computer in Kyoto or Osaka would calculate the value of pi to 10 trillion digits.

I was wrong. The computer that apparently just clinched that record is in Nagano, Japan. And unlike the T2K-Tsukuba System that charted the irrational number in 2009 to 2.5 trillion digits, the latest number-crunching champ isn't a supercomputer--it's a hacked-together PC.

Shigeru Kondo of Iida, Nagano Prefecture, worked with software designed by Northwestern University grad student Alexander Yee, and followed up their 2010 feat of reckoning pi to 5 trillion digits.

The result was achieved earlier this month after 371 days of computation and numerous hard drive failures.

The work was not affected by the March earthquake and tsunami, or by subsequent power shortages, because Nagano is in central Japan and on a different power grid than the disaster zones.

The desktop runs Windows Server 2008 R2 with 3.33GHz Intel Xeon X5680 cores. It required 48 terabytes of hard drive space, with an additional 7.6TB to store the compressed output; as an uncompressed text file, it would be 16.6TB.

The temperature of the computer room shot up to nearly 104 Fahrenheit, or 40 Celsius.

"We could dry the laundry immediately, but we had to pay 30,000 yen ($390) a month for electricity," Kyodo News quoted Kondo's wife, Yukiko, as saying.

What's next for pi? Any takers for 20 trillion digits?