This trick uses a technique known as a "force" -- which means you get a volunteer to pick the card you want, yet they think it was their freewill.
1. Before you introduce the trick, have a peek at the bottom card of the deck.
2. Shuffle the cards in front of the crowd -- but leave the bottom card on the bottom. (practice this so you can do it naturally in front of a crowd)
3. Put the deck face down a table.
4. Name four numbers in the deck, confirming that the number of the card on the bottom is included in this group of numbers.
5. If your card is a Three let's say you specified a Three, Five, Four, and Seven and your 4 numbers. Have a participant select two of the numbers. If the crowd member chose the Five and Five. Say, ''Good' select out of the Three and Four'.
If the participant says three say ''Good, then the bottom card is a Three'.
If they were to announce 'Four', you would still say ''Good, so the bottom card is a Three'.
6. Now instruct the participant to select two of the four suits. If your card is a Three of Spades and they select Hearts and Diamonds, instruct them to select one out of Spades and Clubs. If they say Spades say ''Good, your card is the Three of Spades'.
7. Now turn over the deck and your crowd will be stunned.
The trick is in using logic to get the person to select the card on the bottom of the deck, by leading them with the right questions. This technique is also known as a "force". As you are really forcing the crowd member to select the card you want them too.
Notes: As with all the card tricks on this site, you should have a deck of cards in your hand and go through the motions of performing the trick so that you can understand it easily.