Lots of great, yet simple, card puzzles out there. For a Friday puzzle I'll just re-word one from the 'Math Is Fun' site:
10 cards are placed FACING UP into a normal 52-card deck (42 cards left facing down). The deck is shuffled several times and then handed to a blind man. He is asked to now divide the deck into 2 piles (of any sizes) such that each pile have the same number of cards facing up.
How can he do it?
For the answer, shuffle over to: