Here is an arrangement of 19 cards. What card should go in the bottom right corner?
4♣ 4♠ 3♦ 3♥ 2♥
9♠ 7♦ 6♥ 2♣ 4♥
8♦ 4♥ 5♠ A♣ 7♦
6♥ 3♠ 2♣ 8♦ ?
I agree, Hugo, I'm nowhere near this one. I too initially thought it might belong in Cryptography because of the title, but I'm assuming that it is not. For the sake of argument, there are 4 suits and 9 ranks (A  9) used, which would give 36 unique combinations (26 letters and 10 digits?). In the puzzle, I think only about 16 of them are actually used (I don't feel like counting again!), none appearing more than twice.
If you look at the grid, it begins with patterns of cards sharing the same suit in diagonal rows from bottom left to upper right, but this pattern breaks down by the end...
I thought maybe the rows were math equations with a common result, something like a sum where black cards are positive, red cards are negative, but that didn't seem to work. Or, something like "multiply by spades, add hearts, subtract clubs, etc." but I didn't have much luck there either. If you read them as 4 digit numbers from top to bottom (4986, 4743...), they are descending from left to right, but I didn't immediately see a pattern there either. And that doesn't take into account the problem's title.
Assuming that maybe they really are just playing cards, I can't think of a game that would result in that pattern, and it would require more than one deck since some of the cards are repeated.
So, as you can see, I'm completely lost on this one for the time being...maybe somebody can take these ideas and find something useful...

Posted by tomarken
on 20060316 13:23:05 