I think this is very well known task, but somehow I can't find much information about memorization techniques for cards. You have a deck of 52 cards and they take out one card out of it (51 left). They reveal left each card individually to you, you have to guess the 52nd card. Obviously, we don't want to guess, we want to actually know with 100% certainty.
In the beginning, I tried to actually memorize the cards that went out, but this is quite hard task and quite unreliable too, even though sometimes I guessed the card correctly my precision was around 5%. Then I realized I can solve the problem in very different way, I assocciated [0, 12] values for each rank of card and only thing I needed to count was the sum mod 13. You can guess the 52nd card with just knowing the remainder of the sum, basically if your count is 0, means the 52nd card has rank that's assocciated to 0 (in my case King) and so on. And my precision went up, very close to 100%. But you might've noticed this approach will not give you the suit of the card, therefore I started to think of a way to incorporate this information somehow, though I struggle to come up with efficient (for mental computations) ways to do it.
Does anybody have extra tricks under their sleeves? Or there's no elegant way of doing this?
If you visualize your running sum (mod $13$) as residing at a point of the compass (or at a position around a card table), you can try keeping track of suits by rotating the running sum's position according to the suit (say a quarter turn clock- or counter-clockwise for Hearts and Diamonds, a half turn for Spades, and not at all for Clubs). Mathematically this is equivalent to joriki's suggestion, but it might be easier, mentally, to keep things straight if the two characteristics have a different feel.