British mathematicians teach more magic

The UK-based recreational math channel Numberphile is still on a magic spree. Here they explain a card trick made popular by the Scientific American columnist (and pretty much hero to nerds everywhere) Martin Gardner. 

Again, it's one of those tricks that young aspiring magicians often show me, albeit with different phrases. It's nice for kids because it doesn't require any manual dexterity, but rather remembering a sequence and when to use it. It also provides some immediately feedback. (Either the cards match or they don't and you know right away.)