The positions of the other three visible cards, therefore, must be placed in such a way as to convey a number between 1 and 6. The rule is that the lowest card is revealed, so that the hidden card must be either 1, 2, 3, 4, 5, or 6 values above it. The assistant has a choice about which one to keep hidden and which one to place in the first position We established before that there are at least two cards of the same suit in the five that the assistant saw.
For example, 3 and 10 are six positions apart since we count up from 10: J, Q, K, A, 2, 3. If you choose any two cards, their values can be at most six positions apart. In order, they are: A,2,3,4,5,6,7,8,9,10, J, Q, K.Ĭonsider these values as repeating, as if they are numbers round a clock face, so after K comes A, 2, 3 and so on. The cleverer part is how the other three cards determine the value of the hidden card. When the magician returns he looks at the four cards lined side by side, sees a heart card in position 1 and knows instantly that the missing card is a heart. The assistant hides one of the hearts and puts another of the hearts first in the line. So, the assistant choses one of these cards to be the hidden one, and places the other in a fixed position on the table, say first in the line. Since there are five cards, but only four suits, it must be the case that at least two cards have the same suit. The assistant sees the five cards and has the choice of which four to reveal and which one to keep hidden. How can four randomly chosen cards always identify any of the 48 other cards in the deck?
#NUMBER MAGIC TRICK CODE#
Before I explain the exact method it is worth having a think about what this code might be. There is a code that the magician and the assistant have agreed on beforehand. Or rather, the assistant has placed the four visible cards in a certain way that communicates the value of the hidden card. What the magician has done is to deduce the hidden card from the four visible cards. The audience gasps in awe, since there was no way he knew which cards had been chosen. He glances at the table and – abracadabra – names the hidden card. The assistant takes the cards, looks at them, places one face down, and places the four others face up and side by side.
#NUMBER MAGIC TRICK FULL#
She gives a full deck of cards to an audience member, and asks him or her to shuffle it and then to choose any five cards. Mulcahy calls it Fitch Cheney's Five-Card Twist.įirst the magician leaves the room, leaving the attractive assistant with the audience. It was originally called Telephone Stud since it could be done over the phone. The trick was invented by William Fitch Cheney Jr, a US mathematics professor, in 1951. But I like to aim high, and will assume that she is for the remainder of this post. Okay, the assistant doesn't need to be attractive. The good thing about this trick is that you need an attractive assistant, which is one of the best things about being a magician. Irishman Colm Mulcahy is a legendary cardsmith in the mathe-magical community, and his lovely new book Mathematical Card Magic is jammed with entertaining and thought-provoking tricks. The literature on mathematical magic overwhelmingly concerns tricks using playing cards. And sometimes it relies on genuinely surprising and clever theory.