Instead of the logic riddles, how about something a little more physical. What's the maximum number of times thay you can fold an 11 x 8 1/2 inch sheet of paper in half. In other words, you fold the paper in half once and now have a double thickness sheet of half the area. Fold it again and you have a quadruple thickness sheet one quarter the area. I'll post the world record for folding paper in half in a day or two.