Two logicians place cards on their foreheads so that what is written on the card is visible only to the other logician. Consecutive positive integers have been written on the cards. The following conversation ensues:

A: "I don't know my number."

B: "I don't know my number."

A: "I don't know my number."

B: "I don't know my number."

........ n statements of ignorance later..........

A or B: "I know my number."

What is on the card and how does the logician know it?

(In reply to Attempt by DJ)

This seems rigth, but I think there is more. Each logician knows the others number then they wait for n to reach the other fellows number. Assume x is equal to the number on the other logiacians head. As soon as x-1=n or x=n, then automatically, the logician knows his own number. Since in any situation (I tested this) the logician with the higher number will always see the x-1 or x =n situation first, the logician with the higher number will win. It does not matter if the numbers are even or odd or that A went first.

Posted by Jon on 2003-04-11 06:21:55