Self-working magic
Self-working magic is magic that works simply from following a procedure that is known to the audience. It requires no secret set-up, trickery, sleight-of-hand, or other hidden objects or moves. Some self-working magic allows the audience to have a secret that they do not reveal to the magician until the end. The audience can be told every step, and can even repeat the trick. It can be done alone, since the "magician" may be just as surprised as anybody. All the magician has to do is follow a certain procedure, and everything will be good. Optical illusions and some other science demonstrations could fall into this category. The wonder comes from unexpectedness of a natural phenomenon. Basically, self-working magic relies on some expectation or lack of knowledge in the audience about what produces the outcome. Usually, self-working card tricks revolve around some mathematical principle, such as in the trick "Magical 13", where the spectator is asked to cut the deck 13 times, then split the deck into 13 piles. Upon revealing each pile, it is found that each pile contains only cards of the same value (i.e., one pile has all four fours, the other pile has all four twos, etc.). This is based on the principle that beforehand, the deck is set up with all the suits in order. No matter how many times you cut the deck, the same cards will always be 13 cards away from each other.
Example
Self-working magic tricks can be baffling in a special way. The patter can take different forms that make them more entertaining. One variation of patter is to say that you are hiding nothing, and explaining every step of the trick. Some audience members may still think it is a trick. Another variation, possibly with some tricks, is to say, "I will not be doing the magic, here: you will". Another way of doing it is to make a story that explains—gives a reason to—each step, so that no step is hidden, and the audience can even DO the steps, but the audience members are baffled, anyway.
Story: Make a story of cutting the deck 7 times. 7 drunken sailors decide to play a high-stakes poker game with a new deck of cards. (Use a new deck that is ordered correctly for this game, all cards in order in every suit, not backwards order as some decks have, or have the audience put the cards in order to simulate a new deck). Then say, none of them are in a state of mind to shuffle, so they decide to cut the deck 7 times, one time each. The dealer deals but forgets his own 2nd and 4th cards, so he ends up with 3 cards. He asks for 2 more, but the other sailors refuse, arguing, but none of them want to start the round over. They finally agree to let him get 5 new cards. They make their bets, and each sailor bets high, giving up everything he owns. The dealer bets last, and accepts all the bets. Everybody is all in. Finally, they reveal their cards, the dealer revealing last. Every drunken sailor has a full house. But the dealer rarely loses the hand, having usually a straight flush, and sometimes a royal straight flush. Every step of the trick has been told directly to the audience, but they are still amazed.
No magic, here. Say, "No magic, here. You will tell me which cards you picked." Ask the audience to pick 3 cards, not show them to you, and write them down. Make a pile of 10 cards, a pile of 15, another pile of 15, and a pile of 9, in order (no Jokers in the deck). Ask the audience to place the first card face down on the first deck. Then, take any number of cards from the 2nd deck and place them on the 1st. Put the 2nd card on top of the 2nd deck, and put any number of cards from the 3rd deck onto the 2nd deck. Put the 3rd card on top of the 3rd deck. Now, you put the 4th pile on the 3rd, both on the 2nd, and all 3 on the 1st. You have one deck. Take 4 cards from the top and put them on the bottom. You can tell the audience every step you are doing. Now, you can get 0 points to 3 points. I will go thru the deck, and you grab your cards if you see them. If you grab all 3 by the end, you get 3 points, if you grab 1, you get one point, and so on.
Now, put the 1st card face up, the 2nd face down. They will find no cards. Say that is OK, we will keep going. Pick up the face-down deck and keep going. Do it again, and again. They will never see their card. Stop when only 3 cards are left. And say, gee—only 3 cards left. Turn them over, and there are their 3 cards. It works every single time. Sometimes, you can arrange it so that they do not know that they had to memorize the cards after writing them down. They may pick the wrong cards. Show them that they picked the wrong cards by looking at their paper. They will think the trick is over. Then, reveal the correct 3 cards.
Popular types
1. Steps of math operations that use some secret knowledge of the audience like their birthday, and then reveal that secret knowledge in an unexpected way at the end. For example, think of any secret 3-digit number, multiply it by one specific number, and then another, and it always comes out a 6-digit number with the original 67 -digit number repeated twice.
2. Another one asks the audience to think of words that start with certain letters, and then words linked to the last letters of those words, asking the audience to reveal only their last choices, but somehow almost always ends with the words "Grey elephant in Denmark" even though the audience thought up their own words throughout the steps.
3. Another one ends up with the audience getting all the same number, but it is the WRONG number! Like an optical illusion, people are susceptible to adding up this particular sequence the wrong way almost every time.