ABSTRACT
Most of the puzzle designs included in this book could probably be classifi ed as mathematical recreations, even though very little math may have been involved in designing them, and even less needed to solve them. In this chapter, we make a slight digression into puzzles that depend for their cleverness more on psychology than anything else. First we will discuss what are called Square-Root-Type designs. The idea is not new, but little seems to have been published in the way of exposition or analysis. It is just human nature to fi t square objects into square corners. Not only have all of us been doing it for our entire lives, but also usually it is the only way that makes sense. It applies to everything from desk drawers and bookshelves to buildings and city blocks. Puzzle designers are always looking for ways to exploit these habits of ours. In the fi rst example (Figure 48), fi ve dissimilar pentominoes fi t snugly into a square tray whose dimensions are four times the diagonal of the square building block. Any attempt to fi t the pieces in orthogonally will not succeed, as there is only the one diagonal solution shown. Even when the secret is known, such puzzles can still be entertaining to solve.
