關於

This is like a 2x3x3 Rubik's cube. The sides which are 2×3 can obviously only do half turns. The top and bottom layer have different colours, and the pieces are simply numbered 1-9 with dots. In the solved position, the top layer is simply numbered from left to right, from top to bottom using the numbers 1 to 9. The bottom layer pieces can be solved in two ways. You could give it the same pattern as the top layer, of it could be done in mirror image (right to left, top to bottom). In the latter case, each numbered piece in the top layer should have the same number as the piece directly underneath it. On many dominos it seems that the mirror solution is the intended one, as the number seven corner pieces are reflections of each other. There were mostly two different mechanisms used in the original dominos. The most common use the split-axle mechanism, in which there is a core with four long axles for the sides and which is cut into upper and lower halves for the two layers. These dominos usually have mirror-image sevens on the outside. Rarer is the groove mechanism, as these tend to fall apart when they become worn out. These tend to have identical sevens on the outside. The Magic Domino was patented by Ernő Rubik on 29 March 1983, US 4,378,116. Note that the orientation of the centre pieces do not matter, as the number 5 is represented by a symmetric arrangement of dots. Some rare dominos have pictorial designs on them, and then the orientation of the centres becomes visible. If your browser supports JavaScript, then you can play the Domino by clicking the link below: