## Friday, January 18, 2019

### Any Rubik's Cube can be solved in 20 moves, but it took over 30 years for anyone to figure that out | Strategy - INSIDER

• The Rubik's Cube is an iconic puzzle toy.
• But it is mathematically complicated — there are 43 quintillion possible configurations of the Cube.
• Over 30 years after the Cube was invented, a group of mathematicians showed, using a bank of supercomputers at Google, that any cube could be solved in at most 20 moves.

The Rubik's Cube is a classic puzzle toy invented in 1974 by Hungarian architecture and design professor Erno Rubik, notes Andy Kiersz, senior quant reporter at Business Insider.

 Competitors solve Rubik's cubes as they prepare for the world's largest Rubik's Cube championship in Aubervilliers, near Paris, France, July 15, 2017.Photo: REUTERS/Stephane Mahe
The toy consists of a cube made up of 27 smaller cubes arranged in a 3x3x3 grid with colored stickers on the outer faces of the smaller cubes. A cube starts out in its "solved" configuration with the smaller faces each of the six sides sharing the same color. Each of the six faces of the cube can be rotated freely, moving the smaller cubes around.

The goal of a Rubik's Cube puzzle is to start with some randomized and shuffled messy configuration of the cube and, by rotating the faces, get back to the original solved pattern with each side being a single color.

Actually solving the puzzle is notoriously tricky. It took Erno Rubik himself about a month after inventing the cube to be able to solve it.

Since then, several methods and techniques have been developed for solving a Rubik's Cube, like this basic strategy laid out on the official Rubik's Cube site. Practiced cube-solvers can complete the puzzle in a matter of seconds, with the current world-record holder solving a cube in 3.47 seconds.

Puzzles like the Rubik's Cube are the kind of thing that fascinate mathematicians. The toy's geometrical nature lends itself nicely to mathematical analysis...

As Erno Rubik put it in a recent interview with Business Insider, this question is "connected with the mathematical problems of the cube."

Source: INSIDER

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