Having presented the pack, that the person may choose several succeeding
cards at pleasure, privately observe the card which is above those he
has chosen, and how many he has drawn from the pack; it will then be
easy to count how many spots they ought to contain.
For example, if the observed card be a nine, and four cards have been
drawn, it may readily be seen that those drawn must be a knave,
equivalent to 10 spots: a six, a four, and a two. You may then announce,
that the cards in the person’s hand contain 22 spots.