Remove all of the face cards (jacks, queens and kings) from the deck. This should be done prior to the trick. To ensure the spectator doesn't notice that there are fewer cards in the deck, simply replace the face cards with numbered cards from a second, identical deck.
Hand the cards to your spectator and ask him to give them a quick shuffle. Your spectator will not notice that the face cards are missing for two reasons: First, most people will shuffle the cards face down. Second, as far as your spectator is concerned, the trick hasn't actually started yet, and so he will not be inclined to scrutinize the deck for missing cards.
Take the cards back from the spectator, spread them face down on the table and ask her to pick one. Tell your spectator to shield the card from you so you cannot see it.
Tell the spectator that an ace is worth one point, and that jacks, queens and kings, are worth 11, 12 and 13, respectively. This will further reinforce the impression that the face cards still are in the deck. Ask your spectator to silently multiply the value of his card by two.
Ask your spectator to add five to his total and then multiply the result by five.
Ask your spectator to pick a second card, and then add the value of the second card to his running total.
Ask your spectator to reveal his total. Mentally subtract 25. You will be left with a two-digit number. If you have a two-digit number, the first digit will be the value of the first card the spectator chose, and the second digit will be the value of the second card. For example, if your final total is 93, you can tell your spectator that he picked a 9 and then a 3.
Place a cup and saucer on a table. Remove each of the 8's from the deck. You will place each of them in different locations. Use this simple system to remember where they are. Place the 8 of hearts in your left inside pocket (over your heart). Place the 8 of spades in your shoe. Place the 8 of clubs under either your own or your spectator's chair. Place the 8 of diamonds under your drink. This should all be done before the trick begins. Ensure you use the same deck as before, with all the face cards removed.
Spread the cards face down on the table. Ask your spectator to pick a card and, once memorized, place it on the table face down.
Ask your spectator to multiply the value of his card by nine and then divide the total by two. Then ask him to add all the digits of his number together. He definitely will have a two-digit number, but asking him to add "all the digits" implies that you don't know how many digits are in his running total so far. Then ask your spectator to subtract four from his new total.
Ask your spectator if her number is between one and 26. Ask as if you genuinely aren't sure. Regardless of which card your spectator picked, her final total will be five. When she confirms her number is between one and 26, ask her to change her number for the corresponding letter of the alphabet. She will then pick E.
Ask your spectator to name any card in the deck beginning with the letter he has selected. The only cards that he can pick are the 8 of hearts, diamonds, clubs or spades. Once he has picked, simply reveal the card from either your inside pocket, your shoe, the underside of his chair or from underneath your saucer.