Perfect Card Shuffling
When a standard deck of playing cards undergoes a perfect shuffle, the deck is split evenly in two, a top half and a bottom half. The shuffle interlaces the two halves of the deck perfectly. If the top card of the deck stays on top after this shuffle, the shuffle is referred to as an "out-shuffle". When a deck of cards undergoes eight perfect out-shuffles, every card in the deck will be back in its original position. Each line in the diagram above represents a playing card starting in a particular position and shows where it is after each of eight perfect out-shuffles. Use the "Emphasize a particular card" checkbox to examine the specific positions of any card in the deck after each of the eight out-shuffles.