A certain king offered to give the prince his liberty if he could whittle a plug that would fit four different shaped holes, namely: a square hole, a round one, an oblong one and a triangular one, says the Pathfinder. A broomstick was used to make the plug and it was whittled in the shape shown in Fig. 1. The holes in the different places as shown in Fig. 2, were fitted by this one plug.

Illustration: Fits Four Different Shaped Holes