奇闻：法国天才７２．４秒算出２００位数的１３次方根

武渊涛

French “mathlete” Alexis Lemaire showed off his rare mental agility Thursday, breaking the world record kept by himself after working out in his head the 13th root of a random 200-digit number in just 72.4 seconds.

Lemaire, a 27-year-old doctoral student in artificial intelligence from Reims, near Paris, was presented with the randomly-picked 200-digit number by a computer, which displayed the figure over 17 lines on the screen.

Lemaire 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.

“The first digit is very easy, the last digit is very easy, but the inside numbers are extremely difficult,” the mental gymnast, who says he doesnt consider himself a nerd or a geek, said.

Lemaire, who sports a beard and glasses under thickly-matted eyebrows and a furrowed brow, previously performed the feat in 77 seconds and has been working at the 13th root problem for years, repeatedly eroding his best time.

“I use an artificial intelligence system which I use on my own brain instead of on a computer,” he explained, matter-of-factly.

“Personally, I believe most people can do it but I have also a high-speed mind. My brain works sometimes very, very fast.”

上周四，法国“数学天才”亚历克西斯·勒麦尔展示了其罕见的心算本领，他以72.4秒心算出一个随机抽取的200位数的13次方根，打破了由他本人保持的世界纪录。

27岁的勒麦尔来自巴黎附近的兰斯市，是人工智能专业的一名博士生。这个由计算机随机抽取的200位数在屏幕上显示了整整17行。

而勒麦尔只用了一分多钟的时间就算出了这一长串数字的13次方根，答案是2397207667966701。

换句话说，这个数字的13次方就是计算机抽取的那个200位数。

勒麦尔说：“（在计算过程中，）确定第一个和最后一个数字非常容易，但算出中间的数字相当困难。”这位数学天才说自己并不是个“书呆子”或“怪人”。

勒麦尔留着络腮胡，戴着副眼镜，眉毛浓密，有抬头纹。勒麦尔之前的纪录是77秒。多年来，他一直研究心算200位数的13次方根问题，并多次打破自己保持的纪录。

他不动声色地解释说：“我是用一个人工智能系统计算出结果的，只不过我在大脑中运用这个系统，而不是在计算机中。”

“我相信大多数人都能算出一个200位数的13次方根，只是我的速度稍快一些。我的大脑有时运转得相当快。”