The Rubik's ‘Professor's Cube' is the 5x5 version of the famous Rubik's Cube. The Rubik's 5x5 is not for the faint-hearted and is the most complex of all the Rubik's Cubes. However, knowledge of how to solve the 3x3 Cube and the 4x4 Cube will help you a lot. The full number of permutations for the 5x5 Cube has been calculated at 283 duodecillion on the long scale or 283 trevigintillion on the short scale.