**Alexis Claude Lemaire (1980)**is a French computer scientist and mental calculation champion who holds world records for mentally calculating the integer 13th root of a 100-digit number and of a 200-digit number.

On May 10, 2002 he calculated the 13th root of a 100-digit number in 13.55 seconds, beating the record held by Willem Klein (88.8 seconds) and the somewhat less official record of Gert Mittring (39 seconds). On November 23, 2004 Mittring tried to beat Lemaire's record, but his time of 11.8 seconds was not counted as official as the organization's rules had decided to stop recognising records for root extraction of random numbers due to the difficulty of standardising the challenge. Less than a month later Lemaire beat his own record with a time of 3.625 seconds - that's all it took for him to read the number, calculate its root, and recount the answer. He found the 13th root of the 100-digit number 3,893,458,979,352,680,277,349,663,255,651,930,553,265,700,608,215,449,817,188,566, 054,427,172,046,103,952,232,604,799,107,453,543,533, which is 45,792,573. However, this record is also unofficial.

Following this achievement, Lemaire gave up trying to improve his performance at calculating roots of 100-digit numbers, and moved on to 200-digit numbers. Like an athlete, he trains his brain daily for this task. On April 6, 2005 he calculated the 13th root of a 200-digit number in 8 minutes 33 seconds. By July 30, 2007 Alexis got his time down to 77.99 seconds at the Museum of the History of Science, Oxford and by November 15 his time was further decreased to 72.4 seconds. His latest achievement came on December 10, 2007 where he mentally extracted the 13th root of a random 200-digit number in 70.2 seconds. The so-called 'mathlete' produced the answer of 2,407,899,883,032,220 at London's Science Museum.

A computer was used to produce the random 200-digit numbers he tried to extract the 13th root from. The museum's curator of mathematics 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 says that his mental feats also have very useful applications in artificial intelligence, his chosen field.

**Shakuntala Devi (November 4, 1939)**is an Indian born calculating child prodigy. Her calculating gifts first demonstrated themselves while she was doing card tricks with her father when at the age of three. They report she "beat" them by memorization of cards rather than by sleight of hand. By age six she demonstrated her calculation and memorization abilities at the University of Mysore. At the age of eight she had success at Annamalai University by doing the same.

Unlike many other calculating prodigies, her abilities did not wane in adulthood. In 1977 she extracted the 23rd root of a 201-digit number mentally. On June 18, 1980 she demonstrated the multiplication of two 13-digit numbers 7,686,369,774,870 x 2,465,099,745,779 picked at random by the Computer Department of Imperial College, London. She answered the question in 28 seconds. However, this time is more likely the time for dictating the answer (a 26-digit number) than the time for the mental calculation (the time of 28 seconds was quoted on her own website). Her correct answer was 18,947,668,177,995,426,462,773,730. This event is mentioned on page 26 of the 1995 Guinness Book of Records with ISBN 0-553-56942-2.

In 2006 she released a book called In the Wonderland of Numbers with Orient Paperbacks which talks about a girl Neha and her fascination for numbers.

**Truman Henry Safford (January 6, 1836)**was an American calculating prodigy.

At an early age he attracted public attention by his remarkable calculation powers. At the age of nine, a local priest asked him to multiply 365,365,365,365,365,365 by itself. In less than a minute he gave the correct answer of 133,491,850,208,566,925,016,658,299,941,583,225. At around this age he also developed a new rule for calculating the moon's risings and settings, taking one-quarter of the time of the existing method.

Unlike many other calculating prodigies, Safford did not give public exhibitions. He went to college and studied astronomy. He became the second director of the Hopkins Observatory at Williams College, the oldest extant astronomical observatory in the United States. He served as director of the Observatory until his death in 1901. The Safford Fund for Williams College student researchers was created by his descendants to honor him. A portrait of him as a child prodigy hangs in the Hopkins Observatory's Mehlin Museum of Astronomy, adjacent to the Milham Planetarium. His natural calculating abilities seemed to wane with age.

Source en.wikipedia.org

## No comments:

## Post a Comment