The History and Evolution of Playing Cards
playingcarddecks.com
playingcarddecks.com
Entertainment of course - single and multiplayer, chance and betting, mathematics of all kinds, throwing, building (like a house of cards). I thought it was so cool when a character in Cryptonomicon used it to create an encryption cypher from jail.
A sufficiently randomly shuffled deck of cards is almost certainly in an arrangement that has never existed before and will ever exist again.
52 cards divides evenly by 2, 4, 13, 26. Add two jokers and you get 3, 6, 9, 18. Remove the faces and you get even more.
Its just so well designed - or evolved as it were. If you could only have one object for the rest of your life to entertain or educate you, I dont think you could do much better than a deck of cards.
John Scarne wrote extensively on this in his various books --- _Scarne on Cards_ is well-worth reading, and in particular, speaks of the need for practice and repetition to develop the dexterity and feel necessary for card manipulation/tricks.
What about a computer? If you make the argument that it is a composite of many different elements, so is a deck of cards.
There is a saying in Bridge that each hand you play has almost certainly never been played before and almost certainly will never be played again.