You have a long strip of paper, one piece of tape, and some scissors. You must create two paper rings that are linked. The catch is that you must use the tape before touching the scissors, and you may not tear the tape or paper.
(In reply to re: Solution
A general formula for a ring with n half-twists:
* n is even (n=2*m):
You will get two different rings. The rings are 'through' each other m times, and each has again n half-twists.
* n is odd:
You will get a single ring, with 2*n half-twists.