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.)

(In reply to My 2 cents worth by Richard)

Best way to understand is if hypothetically we were to cut another circle over the one refered, to form a ring. Consider the thickness of this ring to be very small ( 1mm). If you hold the ring from one edge and stretch it from the other diametric end you can pass a thin coin almost equal to half the circumference of the inner circle. 

Posted by Salil on 2006-05-29 18:35:32