This order may be instantly recalled by using as a memory-peg the word CHaSeD, which contains the initials of the four suits in the proper order, or the reader may if he prefers it recall them by reflecting that Cool Heads Soon Decide.

The arrangement of each suit follows the natural order, the ace of clubs being No. 1; the deuce 2; and the trey 3; knave 11; queen 12 and king 13. The card next following, viz., the ace of hearts, will be 14; the deuce of hearts 15, and so on, the complete arrangement being as shown below:

The arrangement of the table being once understood, the number associated with any given card in the club suit suggests itself automatically, e.g., the seven of clubs is likewise No. 7 in the list. To ascertain the name of the card corresponding to any of the higher numbers, all that is needed is to subtract from that number 13, or such higher multiple of thirteen as the case will admit, and the difference will represent its position in its own suit.

Suppose, for instance, that the performer desires to know what card answers to the number 20. Deducting thirteen from 20, the remainder, 7, tells him that the card is the seventh (i.e. the seven) of the second suit, viz., hearts. If he wants to know the name of No. 29, he deducts 26, when the remainder, 3, tells him that the card is the three of the third suit, spades. If the card be No. 40, the number to be deducted will be 39, and the remainder, 1, tells him that the card is the first of the fourth suit, viz., the ace of diamonds. After a very few trials, this little exercise in mental arithmetic becomes so familiar that the calculation becomes practically instantaneous.

Going a step further; with each of the six pages of the pocket-book is associated a special number, known as its “key” number. These are as under:

Page 1Key Number1
” 2” ”2
” 3” ”4
” 4” ”8
” 5” ”16
” 6” ”32

The memorising of these is also a very simple matter, for it will be noted that the key numbers are the first six factors of the familiar geometrical progression, 1, 2, 4, 8, 16, 32. Printed as below:

1,2,3,4,5,6
1,2,4,8,16,32