Arrange each heap of cards in such a manner that the spots on the bottom
one, added to the cards above it, may always amount to twelve; continue
to make as many heaps as possible, in the manner above prescribed, and
place the remaining cards on one side. Then separate in your mind four
heaps, and multiply the heaps which remain, after these are deducted, by
13; this product, added to the number of cards, will be that of the
spots required. We give the solution of this problem by an analysis in
“To Guess the Spots on a Card,” p. 253.
[Illustration]