2x2x2 Rubik's Cube

The 2x2x2 Rubik's Cube is also known as a "Pocket Cube" and a "Mini Cube".

Invention and the Creator
In March 1970, Larry D. Nichols invented a 2×2×2 "Puzzle with Pieces Rotatable in Groups" and filed a Canadian patent application for it. Nichols's cube was held together by magnets. Nichols was granted U.S. Patent 3,655,201 on April 11, 1972, two years before Rubik invented his Cube. Nichols assigned his patent to his employer Moleculon Research Corp., which sued Ideal in 1982. In 1984, Ideal lost the patent infringement suit and appealed. In 1986, the appeals court affirmed the judgment that Rubik's 2×2×2 Pocket Cube infringed Nichols's patent, but overturned the judgment on Rubik's 3×3×3 Cube.

Facts
The 2x2x2 Rubik's Cube has 8 pieces, all of them are corner pieces.

The 2x2x2 Rubik's Cube has 3,674,160 possible combinations.

The world record solve for a 2x2x2 Rubik's Cube is 0.49 seconds, set by Maciej Czapiewski of Poland on 20 March 2016 at Grudziądz Open 2016.

The 2x2x2 Rubik's Cube can always be solved in 11 turns or fewer.

Methods
A 2x2x2 Rubik's Cube can be solved with the same methods as a 3x3x3 Rubik's cube, simply by treating it as a 3x3x3 with solved "invisible" centers and edges. More advanced methods combine multiple steps and require more algorithms. Ortega method (also called Varasano method) is an intermediate method. First a face is built (but the pieces may be permuted incorrectly), then the last layer is oriented (OLL) and lastly, both layers are permuted (PBL). Ortega requires a total of 12 algorithms. The CLL method (corners of the last layer) first builds a layer (with correct permutation) and then solves the second layer in one step by using one of 42 algorithms. The most advanced method is the EG method (Erik-Gunnar method), which also starts by building a face (in any permutation), but then solves the rest of the puzzle in one step. It requires knowing 128 algorithms, 42 of which are the CLL algorithms.