French "mathlete" Alexis Lemaire showed off his rare mental agility Thursday, claiming a new world record after working out in his head the 13th root of a random 200-digit number in just 72.4 seconds... The number was so long it ran over 17 lines. Lemaire, who says he doesn't consider himself a nerd or a geek, then took just over a minute to identify two quadrillion, 397 trillion, 207 billion, 667 million, 966 thousand, 701 as the 13th root. In other words, the number multiplied by itself 13 times produces the 200 digit number originally generated by the computer... "I...