52 numbers, 4 spectators, 1 magician.
And a 1 in 6.5 million chance!

The magician showed a well-shuffled deck of cards, with numbers from 1 to 52 on the back. He took a piece of paper and wrote a prediction. Not entirely satisfied, he took another piece of paper and wrote a second prediction, noting that one of the predictions would probably turn out to be correct later. Both predictions were placed in a visible location. Four spectators were then asked to name one card each.

The magician removes the four named playing cards from the deck and turns them face down, revealing their numbers. Together with the audience, these four numbers are added together to give, for example, 115. Remarking that at least one prediction is correct, the magician turns one of the predictions over: It reads 115!

After a brief hesitation, as an afterthought, the magician turns over the other prediction. It shows all four numbers chosen by the audience! A perfect match!

Phoenix, red back, normal index

One of the most puzzling things I saw at FFFF!
Robin Dawes, Linking Ring