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Home > How to solve the Rubik's Cube
This page describes one method of solving the popular Rubik's Cube puzzle. It is not the only method.1 Background
The following is one of many solutions to the Rubik's Cube.
This solution was developed by David Singmaster , a British mathematician.
Before starting, a method is required for describing the various moves that will be made. There are six faces, with the following notations:
- Upper, or top face = U
- Down, or bottom face = D
- Left face = L
- Right face = R
- Front face = F
- Back face = B
Each face can be turned either clockwise or counter-clockwise, with respect to its center (i.e. a move that may be clockwise to the viewer when looking at the cube, may not be clockwise for that face, in relation to the middle of the cube).
The names for the different kind of moves (the U face will be used as an example) are:
- A 90-degree turn clockwise on a face, is denoted by U.
- A 90-degree turn counter-clockwise on a face is denoted by U' ("U prime") (Also note this is the same as U, done three times).
- A 180-degree turn either clockwise or counter-clockwise on a face, is denoted by UČ ("U squared") and is the same as two clockwise turns, or two counter-clockwise turns.
The individual pieces can be referred to by a two-letter (for edges) or three-letter (for corners) combination. For example, the piece in the upper right front corner is called URF, and the edge piece to the down and left of the cube is called DL. These notations refer to the piece that is in that place at that time, not the piece that should go there.
These six moves ( U D L R F B ) moves, and any sequence of moves, do not move the position of the 6 center pieces. (They rotate the center pieces. This solution assumes that the rotation of these center pieces is unimportant.)
1.1 Other terms
- Cubelet
- There are 27 of these, one of which is hidden in the middle of the cube, and 6 more of which (the centers of the faces) are probably never referred to at all. The rest of them move about the cube freely.
- Corner
- A cubelet at the intersection of three faces. May be referred to by the names of the three faces that meet there. For example, UFR and DBL are corners.
- Edge
- The three cubelets comprising the intersection of two faces. May be called by the names of the two intersecting faces; for example, UF and FR are edges. May also refer to the edge cubelet.
- Edge cubelet
- The middle cubelet of the three on an edge. May also be called the edge.
- Face
- One of the six surfaces of the cube. The faces are called U (top), D (down), R (right), L (left), F (front), and B (back), relative to the orientation of the cube in your hand.
- Slice
- Also layer or slab. Nine cubelets. The 3x3 cube is 3 slices deep any way you look at it. The slices are numbered 1, 2 and 3, relative to a face. If slice(s) are not specified in a move, it means slice 1, i.e., the face itself.
2 Step 1: Top edge pieces
The cube is assumed to be scrambled. The first thing to do is to chose a color, say white (it tends to stand out from the other colors on the cube).
It's also a very good idea to always do a specific color first, since it will soon be learnt which colors are adjacent, which speeds things up considerably.
The first step is to form a cross on the top face of the cube.
Orient the cube so that the white center piece is on top.
The aim is to get the correct pieces in the UL, UB, UR and UF locations.
So, some of the following moves are needed: (be sure to do those in the first step first).
- If a white-other color (OC) piece is on the U face:
- If white is in the U position, simply rotate the U face until the OC is lined up with its center.
- If OC is in the U position, rotate the U face so that the piece is at an adjacent edge location to its desired location. Hold the cube so that white is the U center and OC is the F center. Now rotate U so that the white-OC piece is in the UR position. Now apply R' F'.
- If a white-OC piece is in the middle slice of the cube (the middle third):
- Hold the cube so that white is still on the U face, but this white-OC piece is in the FR location. Now, move it to the U face by applying F' (if the white face is on the R side) or R (if the white face is on the F side). Find the spot where that white-OC piece should go. Rotate U until either F' or R can be applied to move the white-OC piece in the correct spot, so that the white face will move to the top. Example 1: The piece in FR has to be moved, with white being the R face, to its home location at UL, so apply U' F' U. Example 2: FR has to be moved, with white being the F face, to its home location at UL, so apply UČ R UČ. Notice how U is simply moved, then bring the edge piece up to the U face, then move U back to restore the original position, plus the piece just moved.
- If a white-OC piece is on the bottom slice of the cube:
- If the white is on the D face, simply rotate D until the OC is directly underneath its center, and apply FČ (assuming the piece is at the FD position) to put it in the correct location.
- If the OC is on the D face, hold the cube so white is the U center, and OC is the F center. Rotate D so that the white-OC piece is in the RD position, and apply R F' R' (R' is not needed if the UR piece has not been placed correctly yet).
There should now be a white cross formed on the top of the cube.
By now, it will be possible to think how the edge pieces are located relative to one another, which should speed things up.
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