Mental calculators were in great demand in research centers such as CERN before the advent of modern electronic calculators and computers... The world's best mental calculators are invited every two years to compete for the Mental Calculation World Cup... These math prodigies achieve blood flow to parts of the brain responsible for mathematical operations at six to seven times the typical flow... In Frank Herbert's novel Dune, specially trained mental calculators known as Mentats have replaced mechanical computers completely...More at Wikipedia, including a list of famous human calculators.
This guy is good.
ReplyDeletehe probably uses Doomsday Algorithm
He is real fast though.
This guy is amazing! As a matter of fact, I got to see this guy do his stuff in Las Vegas on Thursday, June 19, 2008 right after the reception at The Amaz!ng Meeting 6. At the end of his show, he explained how to square two digit numbers in your head. Now, if only I could remember how to do it...
ReplyDeleteI think he uses a factoring method. 73 squared becomes (70+3)(70+3) which is 70 squared + 70x3x2 + 2 squared. I think I heard him muttering something like that during the TED talk presentation.
ReplyDeleteFor squares ending in 5 it's even easier because the central pair can be cancelled out. 85 squared is (80+5)(90-5) = 7225. Anyone should be able to do those in their head.
typo above. should read "3 squared" rather than "2 squared."
DeleteSmall world - my ex-wife went to school with him, and I live next door to his mother.
ReplyDelete