The Pentacube set is illustrated on the next page. The set contains 29 pieces. They are all the possible structures Constructible by connecting 5 cubes together facewise. Twelve Pieces are flat pieces known as Pentominoes. Of the three dimensional pieces, five are achiral ( i.e. symmetrical) and six pairs of chiral pieces. Pentominoes have standard names based on similarities to letters of alphabet, which are used here with slight change. The pieces are referred to by their names in quotes e.g., “I” refers to the straight piece. Chiral pairs are designated by a prime sign, e.g., “E” and “E”‘. In order to be able to show three dimensional pieces, a cross over a cube shows another cube on top, and a cross with a square hole inside designates an empty space underneath.