Not so smart From Sir Graham Sutton. FRS
Sir: In his review of Leo Talamonti's Forbidden Universe (December 14) Mr Colin Wilson isimpressed by the feat of the calculating prodigy Zerah Colbum born 1812) in finding a factor of "a vast number, over four thousand million" in a few seconds. But Colburn was simply repeating a well known result. The number 641 divides exactly the fifth of Fermat's Numbers (232 + 1 = 4294,967297) and thus disproves Fermat's conjecture that all these numbers are prime. This was demonstrated in 1732 by Euler, and later Kraitchik. showed how this can be verified easily (by someone familiar with the theory of numbers) without doing any actual division. Because of his interest in large numbers Colburn had almost certainly heard of Euler's discovery, and having an exceptional memory for figures was able to give the answer immediately. Colbum certainly had a remarkable facility for factorizing large numbers in his head, but according to Rouse Ball (Mathematical Recreations and Essays) found it difficult to go beyond 1,000,000, There are to-day several books on so-called 'supernatural' phenomena, but many of the statements are highly suspect or else capable of a simple explanation by professionals. My advice is to take all of these marvels with a large pinch of that essential but now somewhat scarce commodity, salt. 0. G. Sutton. 4 The Bryn, Swansea
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