Arthur Benjamin: Lightning calculation and other "Mathemagic"

Cool

The phonetic alphabet is really useful for memorising numbers really fast but if unfortunately not know of much. Once you take the ten digits and convert them to the most often used phonetic sounds (not including vowels) you can convert any number into a word in a matter of seconds and remember it for good by picturing the word in a ridiculous situation. "Cookie" is 77 (k sound to 7) and "Fission" is 802 (8 to f, 0 to s, 2 to n). He probably imagined cookies being spilt by machines. :P +practice

at first i was like ok he knows the answers from before but then i was like ok srsly wtf

He could have corrected himself had he given himself a little time to mentally check his answer. Maybe that mistake is proof that he is a genius!!!

OMG. Omg. omg.

The missing digit trick actually isn't that tricky at all. Notice that the number he started with was a multiple of 9. that means any of their numbers must also be a multiple of nine. If a number is a multiple of 9 then the digits add up to 9. All he had to do was add the 6 digits read to him and figure out what digit was needed to get a multiple of 9. Still a clever trick though.

OK it's very nice and entertaining, BUT I thought the point of TED was to spread ideas... so it would be interesting if he explained a little his method!

You can buy his book "Secrets of Mental Math"!

TED also features performances from musicians and the like so a mathemagician would fit right in. however, i do agree that it would have been interesting to know how he actually does those calculations in his head. it's unbelievable!

He is awesome!!!! He did make 2 mistakes though! 457^2= 208,849 and 722^2=521,284.
But he is still very very awesome!!!