Solve a Rubik's Cube in Just 7 Moves

Understanding the 3x3 Rubik's Cube

The classic 3x3 Rubik's cube has 6 colors - white, yellow, blue, green, orange and red. Each of the 6 faces of the cube has 9 stickers of one color arranged in a 3x3 grid. The cube has a total of 26 smaller cubes, called cubies. The center cubies of each face are fixed but the edge and corner cubies can be moved around by twisting the layers of the cube.

The goal of the original Rubik's cube game is to arrange all the cubies so each face has a solid color. This is called the "solved" state. To mix up a solved cube, you twist different layers multiple times to scramble the cubies. Part of the challenge is figuring out how to get the cubies back to their solved positions just by twisting the layers without taking the cube apart.

Understanding a Few Key Concepts

Before learning how to solve the Rubik's cube quickly, you need to understand a couple key ideas that will help the solution make sense:

• Notation - Each move of the cube has a letter denoting which face to turn, and whether to turn it clockwise or counter-clockwise. For example, F means turn the front face clockwise.
• Algorithms - Specific sequences of moves that have a predictable effect on the cube. Memorizing just a few algorithms is enough to be able to solve any scrambled cube.

Solving in Just 7 Moves

It turns out you only need to do 7 moves to solve a Rubik's cube, regardless of how scrambled it is! This works because there are a finite number of possible arrangements of the cubies, and you just need to know how to put them back to the solved state.

The 7 Move Algorithm

Notation:
F - Front face clockwise
B - Back face clockwise
D - Down face clockwise
U - Up face clockwise

The 7 move sequence is:
F D' B2 U B U' B U'

Let's break this down move by move:

1. F - Rotate front face clockwise
2. D' - Rotate down face counter-clockwise
3. B2 - Rotate back face clockwise twice
4. U - Rotate up face clockwise
5. B - Rotate back face clockwise
6. U' - Rotate up face counter-clockwise
7. B - Rotate back face clockwise
8. U' - Rotate up face counter-clockwise

When executed properly on any scrambled cube, this sequence will solve it! It brings all cubies back to their correct positions, though possibly rotated incorrectly still. But getting them in the right places is enough to declare the cube solved!

Why It Works

This is possible because of group theory. All possible cube positions can be categorized into numbered permutation groups. If you analyze these deeply enough, you find that any position can be solved in at most 7 moves. So you just need a 7 move algorithm that hits all possible groups!

Memorizing an algorithm is easier than fully grasping group theory. So just know that math proves it's possible, meaning you only need to remember 7 moves rather than 100+!

Improving Your Speed

With some practice, you can easily solve a Rubik's cube under 10 seconds using just the 7 move sequence. Here are some tips for improving your speed:

Muscle Memory

Drill the sequence over and over without even looking at the cube. Do it while watching TV or listening to music. Get to where you don't need to think consciously about the moves.

Turn Smoothly

Work on turning each face fluidly without pauses between moves. Master a smooth rhythm as you cycle through the sequence.

Lube the Cube

Buy some Rubik's cube lube and apply it liberally on the moving parts. This drastically reduces friction and lets you turn faces rapidly with little effort.

Solve In Your Hand

Practice solving while holding the cube in one hand. This allows you to turn faster than setting it on a table each move.