Mathlete Alexis Lemaire, 27, found the answer to the 13th root to a random 200-digit number using nothing but brain power in 70.2 seconds, beating his previous record of 72.4.
Alexis correctly calculated an answer of 2,407,899,893,032,210 from the possibility of 393 trillion answers.
Lemaire set the world record at London’s Science Museum.
He used a computer package to randomly generate a 200-digit number before calculating the correct answer in just over a minute.
Jane Wess, curator of mathematics at the London Science Museum said: “He sat down and it was all very quiet — and all of a sudden he amazingly just cracked it.
“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; these days there is only a handful. I believe that it is the highest sum calculated mentally.”
Lemaire, who attends the University of Reims, began demonstrating his mental calculation prowess by finding the 13th root of a random 100-digit number.
However, this feat soon became too easy for him and he abandoned trying to improve his time when he calculated an answer in less than four seconds in 2004.
Lemaire broke the record in the Science Museum’s History of Computing gallery, where he had a backdrop of Charles Babbage’s Difference Engine Number Two, the world’s first successful mechanical calculator, designed in the 1840s.