About

This puzzle consists of a square 3×3 tray with eight cubes in it. The cubes are identical, and each side of a cube is a different colour. There are ridges on the base of the tray so if you push a cube towards the vacant space it will easily roll over. By rolling the cubes around they get mixed up. The aim is to arrange them so that the space is in the middle and that the cubes show all the same colour on top. A more difficult challenge is to have the space in the middle and all the cubes in the exact same orientation, i.e. not only do the top faces match, the sides match as well. The puzzle was invented by John Harris, and discussed in Martin Gardner's Mathematical Games column in the Scientific American, March and April 1975. In that original version only the top faces of the cubes are coloured, and the aim is to find the shortest sequence that leaves all the cubes turned upside down, with the gap in the middle. A more difficult version is mentioned too, in which all 24 outwardly visible faces are red, all 24 unexposed faces (i.e. touching faces and bottom sides) are not coloured. Here the aim is to go from being completely red on the outside to completely uncoloured. By the way, the inventor is not the same John Harris who invented the Astrolabacus puzzle. If your browser supports JavaScript, then you can play the Eight Cubes Puzzle by clicking the link below: