The Rubik’s Cube is a 3D mechanical puzzleinvented by the Hungarian architect Ernő Rubikin 1974.

Rubik’s Cube

Its original and simpler version (3×3) – that presents 9 squares on each of the 6 faces, with 54 squares totally – can assume up to 43.252.003.274.489.856.000 positions!

Nonetheless, every position of 3×3 Rubik’s Cube can be solved in 20 moves or less (named “God’s Number”), whereas the maximum number of moves required to solve a Rubik’s cube with N squares per row is proportional to N^{2}/log N.

These two results were found respectively by the cuber Tomas Rokickiand his colleagues in 2010 and by the Erik Demaine‘s (Professor of Computer science and engineering at MIT) research team in 2011.