I'm reading through random articles and here's an interesting one from the Department of Mathematics and Statistics at Stanford University:
"The way that a magic trick works can be just as amazing as the trick itself. My favorite way of illustrating this is to talk about shuffling cards. In this article, I will try to explain how there is a direct connection between shuffling cards and the Riemann Hypothesis — one of the Clay Mathematics Institute’s Millennium Prize Problems. Let us begin with perfect shuffles. Magicians and gamblers can take an ordinary deck of cards, cut it exactly in half, and shuffle the two halves together so that they alternate perfectly as in figure one, which shows a perfect shuffle of an eight-card deck.
If the shuffle is repeated eight times with a fifty-two card deck, the deck returns to its original order. This is one reason that perfect shuffles interest magicians." - Persi Diaconis, Professor of Statistics and Mathematics, Stanford University