Card tricks are often performed by magicians and are a popular form of entertainment. One of the most popular card tricks is the 21 card trick. This trick is easy to learn and can be performed by anyone with a deck of cards. In this article, we will explain how the 21 card trick works using math.
The Setup
The first step in the 21 card trick is to set up the deck of cards. Start by removing all of the face cards (Jack, Queen, and King) from the deck. This leaves you with 40 cards in total. Shuffle the remaining cards and lay them out face down in three piles of seven cards each. The remaining nine cards are placed face down in a separate pile.
The Trick
To perform the 21 card trick, ask someone to pick a number between 1 and 21. Once they have picked a number, ask them to look at the first pile of cards and count down to their chosen number. Then, ask them to remember the card at that position and place the pile back on top of the remaining cards.
Next, ask them to do the same thing with the second pile of cards, counting down to their chosen number and remembering the card at that position. Finally, ask them to repeat the process with the third pile of cards.
After they have remembered their card from the third pile, ask them to tell you which pile their card is in. Once they have told you, take the other two piles and place them on top of the pile that contains their card.
The Math Behind the Trick
The 21 card trick works because of a simple math principle. If you add up the numbers 1 through 6, the total is 21. This means that if the person chooses a number between 1 and 21, their card will always be in the pile that is left over after the other two piles are combined.
For example, if they choose the number 15, their card will be in the pile that is left over after the other two piles are combined. This is because 15 is the 6th number in the sequence 1 through 21. So, they will count down through the first pile to the 7th card, then continue counting through the second pile until they reach the 8th card. Finally, they will count through the third pile until they reach the 15th card, which will be their chosen card.
Variations of the Trick
There are many variations of the 21 card trick that use different numbers of cards or different math principles. For example, some versions of the trick use 27 cards instead of 21, while others use a different math sequence such as the Fibonacci sequence.
Regardless of the variation, the key to the trick is to set up the cards in a specific way and to use a math principle to ensure that the chosen card is always in the pile that is left over after the other two piles are combined.
In Conclusion
The 21 card trick is a classic card trick that has been entertaining audiences for decades. By understanding the math behind the trick, anyone can learn to perform it and amaze their friends and family. Whether you stick to the classic version of the trick or try out a variation, the key is to practice and perfect your technique.
