To name a card that a person may draw from behind the back.
Spread the cards out behind the back in such a manner that when the card is drawn you can separate the deck at the point bringing the two parts in front of you and placing the upper half underneath.
In that way you know that the card the person has drawn should be the one following the bottom card, so that by glancing at the bottom card, adding three to it, and calling the suit that fop lows the bottom card, you will name the card drawn.
EXAMPLE–A person draws a card and on making the shift in front, you find that the bottom card is the nine of diamonds.
You then add three to nine, which is twelve or the Queen (Rule 3), and call it the Queen of Clubs, as Clubs follow Diamonds, and you will have named the card drawn.