This is a card trick which depends upon a certain “key,” the
possessor of which will always have the advantage over his
uninstructed adversary. It is played with the first six of each
suit--the four aces in one row, next row the deuces, threes,
fours, fives and sixes. The object now will be to turn down cards
alternately, and endeavour to make thirty-one points by so turning
without over-running that number. The chief point is to count so as
to end with the following numbers: 3, 10, 17 or 24.
For instance, we will suppose it your privilege to commence the
count; you would commence with 3, and your adversary would add 6,
which would make 9; it would be then your policy to add 1 and make
10; then, no matter what number he adds he cannot prevent you making
17, which gives you the command of the trick. We will suppose he adds
6 and make 16; then you add 1 and make 17; then he to add 6 and make
23, you add 1 and make 24; then he cannot add any number to make 31,
as the highest number he can add is 6, which would only count 30, so
that you can easily add the remaining 1 and make 31.
If your adversary is not wary, you may safely turn indifferent
numbers at the beginning, trusting to his ignorance to let you count
17 or 24; but, as his knowledge increases, he will soon learn that 24
is a critical number, and to play for it accordingly.
If both players know the trick, the first to play must be the winner,
as he is sure to begin with a 3, which commands the game.