Every magician should have a range of card forces in their repertoire. They not only form the basis of hundreds (possibly thousands) of card tricks, they also give you the basis to start inventing tricks of your own. So if you don?t already know how to force a card then you can find out how right now.
Firstly, if you want someone to choose a specific card then place it on the bottom of the pack. If you merely need to know what card they have chosen then sneak a look at the bottom card of the pack.
Now give the pack to a spectator and ask them to cut it, and to place the top section onto the table as in Fig. 1.
Ask them to mark where they cut the cards by taking the top card from the pack in their hand and placing it face up on the tabled cards as shown in Fig. 2. Emphasise that this is purely to mark where they freely cut the pack.
Now ask them to place the cards in their hand onto the tabled cards as in Fig. 3.
Ask the spectator to run through the pack with the faces towards them and to note the card immediately after the face up card (Fig. 4). This of course will be the card that was previously on the bottom. You have now forced your card!