Triskaidekaphobia by Tom Daugherty

Apocalypse by Harry Lorayne
Volume 16, Number 3 March 1993
Page 2191 et seq.

Personal Comment: Kinda interesting if you are interested in mathematical principles. Otherwise really boring... But honestly I think this is a great trick to teach those kids who really beg you to teach them a trick. And I say this having two reasons in mind! 1st: Kids seem to love doing tricks where they don't really know why it works. It leaves some sort of mystery. 2nd: It's very rewarding for a kid to do that trick and have others not knowing how this is done, without the fear of somebody already knowing. Even among magicians this principle is pretty unknown. So this is a great trick for kids. Not for magicians I might add.

Difficulty: Self Working