Some playing cards are being divided into two piles according to a certain rule.

Pile A has

A♥ A♣ 7♥ 9♠ 3♣ 

while Pile B has

A♦ 8♦ 4♠ K♣ 10♥ 

In which pile should the Q♥ be placed according to that rule?

Pile B.

The cards in Pile B, if from a standard deck of playing cards, have rotational symmetry or order 2 (also known as point symmetry) and the cards in Pile A do not. 

If all 52 cards are divided up according to this rule, twenty-two cards will end up in Pile A, and thirty cards will end up in Pile B:

PileA:
Hearts: A, 3, 5, 6, 7, 8, 9
Clubs: A, 3, 5, 6, 7, 8, 9
Diamonds: 7
Spades: A, 3, 5, 6, 7, 8, 9

Pile B:
Hearts: 2, 4, 10, J, Q, K
Clubs: 2, 4, 10, J, Q, K
Diamonds: A, 2, 3, 4, 5, 6, 8, 9, 10, J, Q, K
Spades: 2, 4, 10, J, Q, K

Posted by Dej Mar on 2006-04-07 18:50:22