17. The Arithmetical Puzzle.
This card trick, to which I have alluded in a previous page,
cannot fail to produce astonishment; and it is one of the most
difficult to unravel.
Hand a pack of cards to a party, requesting him to make up
parcels of cards, in the following manner. He is to count the
number of pips on the first card that turns up, say a five, and
then add as many cards as are required to make up the number 12;
in the case here supposed, having a five before him, he will
place seven cards upon it, turning down the parcel. All the
court cards count as 10 pips; consequently, only two cards will
be placed on such to make up 12. The ace counts as only one pip.
He will then turn up another, count the pips upon it, adding
cards as before to make up the number 12; and so on, until no
more such parcels can be made, the remainder, if any, to be set
aside, all being turned down.
During this operation, the performer of the trick may be out of
the room, at any rate, at such a distance that it will be
impossible for him to see the first cards of the parcels which
have been turned down; and yet he is able to announce the number
of pips made up by all the first cards laid down, provided he is
only informed of the number of parcels made up and the number of
the remainder, if any.