June 17, 2005 Science Magazine

Trade secret. A 24-year-old French informatics student has broken his own world record in mental calculation by extracting the 13th root of a 200-digit number. Alexis Lemaire of Reims performed the feat in 4:28 at a mathematics festival in Paris earlier this month. He broke his old record, set in April, by more than 4 minutes.

Aside from the obvious talent for rapid computation and an amazing memory, Lemaire uses an algorithm he developed but has only partially disclosed, says mathematician Jean-Paul Delahaye of Lille Science and Technology University, who was a witness at both events. "It would be very interesting to know how that works," says Delahaye, "because it is adapted to the human brain instead of a computer." Lemaire says he would like to set his next record in the United States. "In France almost everybody knows me now," he says. His winning answer: 2396280083911011.


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