Pocket Cube

2x2x2 combination puzzle From Wikipedia, the free encyclopedia

The Pocket Cube (also known as the 2×2×2 Rubik's Cube and Mini Cube) is a 2×2×2 combination puzzle invented in 1970 by American puzzle designer Larry D. Nichols.[1] The cube consists of 8 external pieces, which are all corners.

A scrambled Pocket Cube (having the Japanese color scheme)

History

Solved versions of, from left to right: original Pocket Cube, Eastsheen cube, V-Cube 2, V-Cube 2b

In February 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 with magnets. Nichols was granted U.S. patent 3,655,201 on April 11, 1972, two years before Rubik invented the 3×3×3 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.[2]

Notation

Notation is based on Singmaster notation. Since turning a layer is functionally equivalent to turning the opposite layer in the opposite direction followed by a cube rotation, only three letters are necessary to represent every possible turn:

  • R represents a clockwise turn of the right face of the cube
  • U represents a clockwise turn of the top face of the cube
  • F represents a clockwise turn of the front face of the cube
  • R' represents an anti-clockwise turn of the right face of the cube
  • U' represents an anti-clockwise turn of the top face of the cube
  • F' represents an anti-clockwise turn of the front face of the cube
  • R2 represents a 180-degree turn of the right face of the cube
  • U2 represents a 180-degree turn of the top face of the cube
  • F2 represents a 180-degree turn of the front face of the cube

Methods

A pocket 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. These algorithms designed for solving a 2×2×2 cube are often significantly shorter and faster than the algorithms one would use for solving a 3×3×3 cube.

The Ortega method,[3] also called the Varasano method,[4] 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). The Ortega method requires a total of 12 algorithms.

The CLL method[5] first builds a layer (with correct permutation) and then solves the second layer in one step by using one of 42 algorithms.[6] A more advanced version of CLL is the TCLL Method also known as Twisty CLL. One layer is built with correct permutation similarly to normal CLL, however one corner piece can be incorrectly oriented. The rest of the cube is solved, and the incorrect corner orientated in one step. There are 83 cases for TCLL.[7]

One of the more advanced methods is the EG method.[8] It starts by building a face like in the Ortega method, but then solves the rest of the puzzle in one step. It requires knowing 128 algorithms, 42 of which are the CLL algorithms.

Top-level speedcubers may also 1-look the puzzle, [9] which involves inspecting the entire cube and planning out the entire solution in the 15 seconds of inspection allotted to the solver before the solve, with the best solvers being able to plan more than one solution, considering movecount and ergonomics of each.

Group Theory

Scrambled Pocket Cube with one layer partially turned

The group theory of the 3×3×3 cube can be transferred to the 2×2×2 cube.[10] The elements of the group are typically the moves of that can be executed on the cube (both individual rotations of layers and composite moves from several rotations) and the group operator is a concatenation of the moves.

To analyse the group of the 2×2×2 cube, the cube configuration has to be determined. This can be represented as a 2-tuple, which is made up of the following parameters:

Two moves and from the set of all moves are considered equal if they produce the same configuration with the same initial configuration of the cube. With the 2×2×2 cube, it must also be considered that there is no fixed orientation or top side of the cube, because the 2×2×2 cube has no fixed center pieces. Therefore, the equivalence relation is introduced with and result in the same cube configuration (with optional rotation of the cube). This relation is reflexive, as two identical moves transform the cube into the same final configuration with the same initial configuration. In addition, the relation is symmetrical and transitive, as it is similar to the mathematical relation of equality.

With this equivalence relation, equivalence classes can be formed that are defined with on the set of all moves . Accordingly, each equivalence class contains all moves of the set that are equivalent to the move with the equivalence relation. is a subset of . All equivalent elements of an equivalence class are the representatives of its equivalence class.

The quotient set can be formed using these equivalence classes. It contains the equivalence classes of all cube moves without containing the same moves twice. The elements of are all equivalence classes with regard to the equivalence relation . The following therefore applies: . This quotient set is the set of the group of the cube.

The 2×2×2 Rubik's Cube, has eight permutation objects (corner pieces), three possible orientations of the eight corner pieces and 24 possible rotations of the cube, as there is no unique top side.

Any permutation of the eight corners is possible (8! positions), and seven of them can be independently rotated with three possible orientations (37 positions). There is nothing identifying the orientation of the cube in space, reducing the positions by a factor of 24. This is because all 24 possible positions and orientations of the first corner are equivalent due to the lack of fixed centers (similar to what happens in circular permutations). This factor does not appear when calculating the permutations of N×N×N cubes where N is odd, since those puzzles have fixed centers which identify the cube's spatial orientation. The number of possible positions of the cube is

This is the order of the group as well.

The largest order of an element in this group is 45. For example, one such element of order 45 is

.

Any cube configuration can be solved in up to 14 turns (when making only quarter turns) or in up to 11 turns (when making half turns in addition to quarter turns).[11]

The number a of positions that require n any (half or quarter) turns and number q of positions that require n quarter turns only are:

More information n, a ...
n a q a(%) q(%)
0 1 1 0.000027% 0.000027%
1 9 6 0.00024% 0.00016%
2 54 27 0.0015% 0.00073%
3 321 120 0.0087% 0.0033%
4 1847 534 0.050% 0.015%
5 9992 2256 0.27% 0.061%
6 50136 8969 1.36% 0.24%
7 227536 33058 6.19% 0.90%
8 870072 114149 23.68% 3.11%
9 1887748 360508 51.38% 9.81%
10 623800 930588 16.98% 25.33%
11 2644 1350852 0.072% 36.77%
12 0 782536 0% 21.3%
13 0 90280 0% 2.46%
14 0 276 0% 0.0075%
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The two-generator subgroup (the number of positions generated just by rotations of two adjacent faces) is of order 29,160. [12]

Code that generates these results can be found here.[13]

Number of Unique States

Here is a table of the number of unique states at each depth under different degrees of symmetry reduction, with one corner fixed. In 6-fold symmetry, the location of the fixed corner is preserved and allows mirrors. In 24-fold symmetry, all reorientations of the cube are allowed, but not mirrors. In 48-fold symmetry, all reorientations of the cube are allowed, including mirrors.

More information depth, no symmetry ...
depth no symmetry 6-fold symmetry 24-fold symmetry 48-fold symmetry
0 1 1 1 1
1 9 2 3 2
2 54 9 9 5
3 321 54 36 19
4 1847 309 132 68
5 9992 1670 529 271
6 50136 8361 2276 1148
7 227536 37943 9768 4915
8 870072 145046 36582 18364
9 1887748 314710 79006 39707
10 623800 104076 26137 13225
11 2644 449 129 77
Total 3674160 612630 154608 77802
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World records

The world record for single solve is 0.39 seconds, set by Ziyu Ye (叶梓渝) of China at Hefei Open 2025 on October 25, 2025. [14]

The world record for average of 5 solves (excluding fastest and slowest) is 0.86 seconds, set by Sujan Feist of the United States at Kids America Christmas Clash OH 2025 with times of 0.86, 1.02, (0.56), (1.42), and 0.70 seconds.[15]

Top 10 solvers by single solve

More information Rank, Name ...
RankName[16]ResultCompetition
1China Ziyu Ye (叶梓渝)0.39sChina Hefei Open 2025
2Hong Kong Sky Guo (郭建欣)0.41s
China Jiazhou Li (李佳洲)China Beijing Winter 2026
4Poland Teodor Zajder0.43sPoland Warsaw Cube Masters 2023
5Georgia (country) Vako Marchilashvili (ვაკო მარჩილაშვილი)0.44sGeorgia (country) Tbilisi April Open 2024
6China Tian Xia (夏天)0.45sChina Hefei Open 2025
China Yiheng Wang (王艺衡)China Beijing Winter 2026
8New Zealand Connor Johnson0.47sNew Zealand Queenspark O'Clock 2025
China Guanbo Wang (王冠博)Australia Northside Spring Saturday 2022
10Spain Aitor Ibañez Larrea0.49sSpain León Open 2025
Poland Maciej CzapiewskiPoland Grudziądz Open 2016
Australia Sebastian LeeAustralia NSW State Championship 2025
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Top 10 solvers by Olympic average of 5 solves

More information Rank, Name ...
RankName[15]ResultCompetitionTimes
1United States Sujan Feist0.86sUnited States Kids America Christmas Clash OH 20250.86, 1.02, (0.56), (1.42), 0.70
2China Yiheng Wang (王艺衡)0.87sChina Beijing Winter 2026(0.55), 0.78, 0.97, (1.28), 0.85
3Singapore Nigel Phang0.90sSingapore Singapore Skewby March 20250.80, 1.05, (1.17), 0.85, (0.72)
4United States Zayn Khanani0.92sUnited States New-Cumberland County 20240.84, (2.69), (0.71), 1.04, 0.88
5Netherlands Antonie Paterakis0.97sSpain Warm Up Portugalete 20240.93, 1.05, (0.66), (1.43), 0.92
Poland Teodor ZajderPoland Energy Cube Białołęka 20240.96, 1.16, 0.78, (2.30), (0.77)
Poland Cube4fun in Bełchatów 20251.02, 0.82, (1.06), 1.06, (0.71)
7United Kingdom Max Tully1.00sUnited Kingdom Stevenage July 2025(1.35), (0.91), 1.10, 0.99, 0.91
8Sweden Emanuel Schelin1.01sSweden Alekuben 2026(0.81), 1.11, 0.85, 1.07, (DNF)
9Australia Roman Rudakov1.02sAustralia Melbourne Cube Days 20241.16, 0.96, 0.94, (1.24), (0.91)
Poland Olaf KuźmińskiPoland Cube4fun Lublin Winter 20261.20, 0.91, (1.39), (0.90), 0.94
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See also

References

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