How long did it take him? 70 seconds
Alexis Lemaire, a 27-year-old Frenchman, correctly calculated the 13th root of a random 200-digit number from a possible 393 trillion answers. The so-called ‘mathlete’ produced the answer of 2,407,899,893,032,210 in 70.2 seconds, beating his previous record of 72.4 seconds, at London’s Science Museum. A computer was used to produce a random 200-digit number before he sat down to calculate the answer in his head.
The museum’s curator of mathematics, Jane Wess, said: "He sat down and it was all very quiet — and all of a sudden he amazingly just cracked it. "I believe that it is the highest sum calculated mentally. "He seems to have a large memory and he’s made this his life’s ambition. It’s quite remarkable to see it happen.
A very small number of people have this extraordinary ability; nowadays there is only a handful." Lemaire, who attends the University of Reims in northern France, began demonstrating his prowess by finding the 13th root of a random 100-digit number but gave up trying to improve his performance when he calculated an answer in under four seconds in 2004.
Like an athlete, he trains his brain daily for the far harder task of finding the 13th root of 200-digit numbers.