Wim Klein
Also known as Willem or William Klein and performed under several stage names, including Pascal, Moos Optel and Ali Ben Achmed.
Born 4 December 1912 in Amsterdam. Died 1 August 1986 (murdered in his Amsterdam apartment).
Employed by the Mathematisch Centrum, Amsterdam (1952-1956) and by CERN, Geneva (1958-1976).
Is one of the very best all-round mental calculators.
Claimed many 'world records'. Among them was the multiplication of two 40-digit numbers in 23 minutes. Klein's answer was incorrect - 13 of the 80 digits were wrong - but was more accurate than what Klein had believed to be the previous best, achieved in c1850 by Johann Dase, who erred in 27 digits. Unbeknown to Klein, Indian calculator Babu Somesh Chandra Bose had performed the same feat in 1922 but without any errors. Inspired by the feats of Mexican calculator Herbert de Grote, Klein set numerous world records for extracting exact roots from huge numbers, some of which appeared in the Guinness Book of Records in the 1970s and 1980s.
References/Links
1.
A Medico-Psychological Account, Followed by a Demonstration of a
Case of Supernormal Aptitude
Proceedings of the Second International Congress on Orthopedagogics,
1949
Berthold Stokvis PDF
2. World record root extraction PDF
3. SPIEGEL PDF