Take a piece of paper and cut out a perfect circle with diameter 1 inch.

What is the diameter of the largest unaltered coin which may be passed through the hole without tearing it?

(Consider the coin to be very thin, and the paper to be very flexible and tear resistant, but not at all stretchy.)

After the hole is made fold the paper in half so that on both sides of the paper you leave same size semicircles. Now by pulling on the other ends of the paper you will get the semicircle curve to become a straight and as the curve was π*1 inch long it will become the diameter for the thin coin. So my guess is that you can put π inch diameter coin throught that hole.

Posted by atheron on 2006-05-29 12:37:56