Extension: The English official name of the third-order Rubik's Cube is named after Professor Rubik, which is the most common Rubik's Cube before. It has three squares on each side. The side length of the official version of the Rubik's Cube is 57 mm, and the total number of changes of the third-order Rubik's Cube is about 230 million. The third-order Rubik's Cube consists of six central blocks, eight corner blocks and 12 side blocks connected by a central axis. When they are connected together, they will form a whole, and either side can rotate horizontally without affecting other squares.
Development history: 1970 In March, Larry Nichols invented the "jigsaw puzzle that can be rotated in groups" and applied for a Canadian patent. It is a 2×2×2 Rubik's cube, but the Rubik's cubes are attracted to each other by magnets. 1972 obtained the American patent, two years earlier than Professor Ern Rubik's Rubik's Cube.