Question

(this is a long question).
-From a deck of 52 cards. Using its numerical value as a start, continue counting until you get to 13, piling each card on top of the previous card face up, ignoring numerical values (e.g. turn up a 7, count "eight", "nine", "ten", "eleven", "twelve", "thirteen". Jacks, Queens, Kings are worth 11, 12, 13 respectively).
-Do this with the whole deck until you run out of cards, and discard the last pile.
-Turn the piles face down, and discard all but 3 piles.
-Turn up the top card on two of the remaining piles.
-Count all the cards in the discard pile. (cont'd)

Answer 1

-Add the values of the two face up cards (e.g. 12(queen) + 7 = 19).
-Add 10 to this sum (i.e. 19 + 10 = 29).
-Subtract this from the number of cards in the discard pile.
-The number you get should be the value of the remaining face down card.

Will this always work? Why?

Answer 2

Try it out with a deck of cards, see what happens :)