English

The 21 Card Trick and its Generalization

Combinatorics 2018-10-22 v3

Abstract

The 21 card trick is well known. It was recently shown in an episode of the popular YouTube channel Numberphile. In that trick, the audience is asked to remember a card, and through a series of steps, the magician is able to find the card. In this article, we look into the mathematics behind the trick, and look at a complete generalization of the trick. We show that this trick can be performed with any number of cards.

Cite

@article{arxiv.1809.04072,
  title  = {The 21 Card Trick and its Generalization},
  author = {Dibyajyoti Deb},
  journal= {arXiv preprint arXiv:1809.04072},
  year   = {2018}
}

Comments

Corrected typos in several pages from \ln to \log

R2 v1 2026-06-23T04:02:52.619Z