John Allen Paulos in his Who’s Counting column at ABC News:
Martin Kruskal, a renowned mathematician and physicist at Rutgers University, died in December 2006. Of his many accomplishments there is an intriguing trick that almost anyone can appreciate.
I explain it here, and, prompted by April Fool’s Day, I also sketch a sort of biblical hoax based on it that I first proposed in my 1998 book “Once Upon a Number.”
Kruskal’s trick can be most easily explained in terms of a well-shuffled deck of cards with all the face cards removed. The deck has 1s (aces) through 10s only. Imagine two players, Hoaxer and Fool. Hoaxer asks Fool to pick a secret number between 1 and 10…
More here.