The "shoe magic" trick is making its way around the Internet. (See above.) It's a nifty little math trick, and it does indeed work (most of the time). I will first use my own data to demonstrate. I ...

Start with a deck of cards. Before the trick, sneak a peek at the 10th card in the deck. Memorize it. Ask your volunteer to add the first and second digit of their number together. For instance, if he ...