it's hip to do squares // linkage - Lograh
9:02 - it's hip to do squares // linkage
here, and you can hear it straight from the web page. It's a performance/talk by Arthur Benjamin, a self-proclaimed Mathemagician. He does crazy "mental math", squaring four and even five digit numbers in his head, generating 4x4 magic squares on the fly, and other fun stuff. He also answers some questions on how to do all this. The best part, though, is his presentation. It is all pure showmanship, and had me laughing the whole time on the way home.
Obviously more entertaining, perhaps, if you have some interest in numbers to begin with, but there's a chance number-phobic folks will still get a kick out of it due to his delivery.
edit: yes, the show is a year old, but it's still a good listen.