Materials: Dry napkin, pencil or pen

The trick: Mark a dot in the middle of a napkin and, without lifting the pencil or pen, draw a circle around the dot. There should be no lines connecting the dot and the circle.

How to do it: Begin by folding in a corner of the napkin to the center of the square. Draw a dot at the napkin’s center, ending with the pen on the tip of the folded corner. Keep the pen on this corner while slowing easing the corner of the napkin away from the dot. At any distance away from the dot, draw a circle. At no point did the pen have to leave the surface of the napkin.