The card trick mentioned is fun to ponder. Here's a link that gives the full article: <a href="http://courses.csail.mit.edu/6.042/fall09/cardTrick.pdf" rel="nofollow">http://courses.csail.mit.edu/6.042/fall09/cardTrick.pdf</a><p>"You, my friend, are about to witness the best card trick there is. Here, take this ordinary deck of cards, and draw a hand of five cards from it. Choose them deliberately or randomly, whichever you prefer -- but do not show them to me! Show them instead to my lovely assistant, who will now give me four of them, one at a time: the 7 of Spades, then the Queen of Hearts, the 8 of Clubs, the 3 of Diamonds. There is one card left in your hand, known only to you and my assistant. And the hidden card, my friend, is the King of Spades."