Card tricks can be of the usual pick a card, any card variety or something completely different -- Cardini, for example, was renowned for his ability to make cards appear from nowhere while wearing gloves.

Combine some alcohol, two or more people and a pack of cards and one of them is certain to volunteer a trick or two.

Card tricks found on Everything2:

• The Hotel Manager and the Bellhop Card Trick
• How to win bets and make enemies with a simple card trick

First, you need some supplies. Namely, a deck of cards. If you'd like to play along at home, go get one now. I can wait.

*taps foot whilst various Everythingians scramble to get some cards*

Okay, dandy. Let's begin.

This is a cool 'find that card!' card trick, where you'll be able to tell someone what value the top card of a pile (you get to make piles, too! Funfun!) is. There's most likely something mathematical involved, (and, from looking at the other card tricks here on E2, it probably involves modulus stuff), but I'm not sure what it is. If anyone knows, I'd be much obliged if they'd node it here as well.

So anyway, on to the trick!

Flip the top card of the deck over, so it's face-up on the table/desk/floor/ceiling/whatever available, reasonably flat surface you happen to be by right now. I'll do it too, to demonstrate:

 _________
|7        |
|♥        |      
|         |     Well, lookee here, I got a 7.
|         |
|        ♥|
|        7| 

 ___________________________
|7 |6 |K |8 |7 |4 |J        |    
|♥ |♥ |♠ |♣ |♦ |♣ |♦        |
|  |  |  |  |  |  |         |
|  |  |  |  |  |  |         |
|  |  |  |  |  |  |        ♦|
|  |  |  |  |  |  |        J|

 _________
|         |
|  Back   |      
|   of    |   Now doesn't that look pretty?
|  Pile   |
|         |
|         |

 _________       _________       _________
|         |     |10       |     |8        |
|  Back   |     |♠        |     |♦        |
|   of    |     |         |     |         |
|  Pile   |     |         |     |         |
|         |     |        ♠|     |        ♦|
|         |     |       10|     |        8|

Do as I do

Here's an easy but surprisingly effective card trick, called 'Do as I do'. I'll explain the effect first (i.e. how the audience see the trick) and then explain how it's done.

Effect

The magician asks for a volunteer. The magician has two decks of cards, and lets the volunteer choose one. The magician takes the other.

(Now for some patter). The magician explains that this is a demonstration of sympathetic magic. The magician will mimic the the volunteer's actions throughout the trick, resulting in a final magical effect. These are the actions the magician instructs:

1. The magician shuffles his/her deck, and instructs the volunteer to do the same with his/hers.
2. They exchange decks.
3. They shuffle the decks again.
4. They exchange decks.
5. They both pick a card from their own deck, and place it on top. They cut the deck to hide the card.
6. They exchange decks.
7. They each look through the deck for 'their' card.

The magician then gives some more patter about sympathetic magic, before asking the spectator to reveal his/her card, at the same time as the magician reveals his/hers, on a count of three. Magically, the cards are the same!

Method

The magician simply notes the card on the bottom of their own deck at the end of step 3. In step 4, the magician pretends to carefully choose a card, but needn't even remember it. When the volunteer cuts the deck in step 5, he or she will put their chosen card next to the card the magician noted, making it easy for the magician to pick that card out for the finale.

It's hardly rocket science, but there's sufficient messing about to distract the audience from the fact that you're performing an extremely simple trick.

The first bit of the trick is the showbiz. The miracle killer is at the end. The principle of the thing can be explained with this example: Lets pretend a deck of cards is broken into two piles. There's a pile of cards in your hand and one on the table. The card on top of the pile on the table is 13-the number of cards in that pile. You want to know how many cards are on the table. What do you do? You count how many you have in your hand. Then you know that 52 minus this number is the number on the table. Well, in our trick, because of the nature of the set-up, because we know that the number on top of a pile is 13- the number of cards in that pile, you can say that if you have 50 cards in you hand, there would be an 11 on top of the pile (because 2=13-11).

Now in the trick, you know the total number of cards not in the mystery pile is (13-#in pile 1) + (13-#in pile 2) + #of cards from other collected piles (each of these terms is known!!!). That means, the number on the top of the mystery deck must be (13- {52-the number of cards not in the mystery pile}. Since 13 and 52 are also known quantities, the number on the top of the mystery deck is also knowable. All you have to do is count. If you want a more rigorous definition, solve algebreically substituting in all the terms for "the total number of cards not in the mystery pile."