Dasyurus Maculatus
April 25th, 2005, 08:38 AM
A white computer science student has stunned the world of mathematics by working out the 13th root of a 200-digit number in his head in under nine minutes.
By arriving at the 16-digit answer from 390 trillion possibilities, Monsieur A.Lemaire, 24, pulled off the most difficult feat of mental arithmetic ever attempted.
Mr Lemaire was presented with a random 200-digit sprawl on a computer and asked to work out its 13th root. The answer, multiplied by itself 13 times, would match the figure on the screen.
Thirteenth roots are a yardstick in mental arithmetic, because 13 is a prime number whose roots cannot be obtained by combining those of other numbers.
Mr Lemaire has spent four years developing a secret matrix technique in which he memorises thousands of inter-linked tables of numbers to aid his calculations. "It's just like learning your times tables really," he said. "But the numbers are bigger." In December, he took only 3.62 seconds to find the 13th root of a 100-digit number, obliterating the previous record of 13.55 seconds held by a German, Gert Mittring.
"It's all about thinking visually," he said. "I have a map or matrix in my head of thousands of tables that I have learned side by side. I can scroll through them and pick out the numbers I need.
"Above all, you need to link the different items. If you forget something, you have lost the link to that memory, but if you have created several links, even if one breaks you can choose another route," he said.
Scientists at Caen University who studied the brain activity of a fellow prodigy, Rudiger Gamm, from Germany, concluded that such arithmeticians coached their brains to behave differently.
"Training has modified the brain's wiring and the size of cerebral areas," said Bernard Mazoyer, who runs a brain imaging centre at Caen.
Mr Lemaire now wants to find practical uses for his skill: learning 40 languages simultaneously or becoming a "card sharp" to clean up at poker.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/04/24/wmath24.xml&sSheet=/news/2005/04/24/ixnewstop.html
By arriving at the 16-digit answer from 390 trillion possibilities, Monsieur A.Lemaire, 24, pulled off the most difficult feat of mental arithmetic ever attempted.
Mr Lemaire was presented with a random 200-digit sprawl on a computer and asked to work out its 13th root. The answer, multiplied by itself 13 times, would match the figure on the screen.
Thirteenth roots are a yardstick in mental arithmetic, because 13 is a prime number whose roots cannot be obtained by combining those of other numbers.
Mr Lemaire has spent four years developing a secret matrix technique in which he memorises thousands of inter-linked tables of numbers to aid his calculations. "It's just like learning your times tables really," he said. "But the numbers are bigger." In December, he took only 3.62 seconds to find the 13th root of a 100-digit number, obliterating the previous record of 13.55 seconds held by a German, Gert Mittring.
"It's all about thinking visually," he said. "I have a map or matrix in my head of thousands of tables that I have learned side by side. I can scroll through them and pick out the numbers I need.
"Above all, you need to link the different items. If you forget something, you have lost the link to that memory, but if you have created several links, even if one breaks you can choose another route," he said.
Scientists at Caen University who studied the brain activity of a fellow prodigy, Rudiger Gamm, from Germany, concluded that such arithmeticians coached their brains to behave differently.
"Training has modified the brain's wiring and the size of cerebral areas," said Bernard Mazoyer, who runs a brain imaging centre at Caen.
Mr Lemaire now wants to find practical uses for his skill: learning 40 languages simultaneously or becoming a "card sharp" to clean up at poker.
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/04/24/wmath24.xml&sSheet=/news/2005/04/24/ixnewstop.html