The secret is very simple. It consists merely in multiplying the
number of parcels over four by 13 (or rather vice versa), and
adding the remaining cards, if any, to the product.
Thus, there have just been made up seven packets, with five cards
over. Deducting 4 from 7, 3 remain; and I say to myself 13 times
3 (or rather 3 times 13) are 39, and adding to this the five
cards over, I at once declare the number of pips made up by the
first cards turned down to be 44.
There is another way of performing this striking trick. Direct
six parcels of cards to be made up in the manner aforesaid, and
then, on being informed of the number of cards remaining over,
add that number to 26, and the sum will be the number of pips
made up by the first cards of the six parcels.
Such are the methods prescribed for performing this trick; but I
have discovered another, which although, perhaps, a little more
complicated, has the desirable advantage of explaining the