V-Cube 6 to the internal mechanism, thus making the puzzle more durable. The V-Cube 6b, which has the same "pillowed" shape as the V-Cube 7, was introduced later. There are 8 corners, 48 edges and 96 centers. Any permutation of the corners is possible, including odd permutations. Seven of the corners can be independently rotated, and the orientation of the eighth depends on the other seven, giving 8!×3 combinations. There are 96 centers, consisting of four sets of 24 pieces each. Within each set there are four centers of each color. Centers from one set cannot be exchanged with those from another
Two-cube calendar Two-cube calendar A two-cube calendar is a desk calendar consisting of two cubes with faces marked by digits 0 through 9. Each face of each cube is marked with a single digit, and it is possible to arrange the cubes so that any chosen day of the month (from 01, 02, ... through 31) is visible on the two front faces. A puzzle about the two-cube calendar was described in Gardner's column in "Scientific American". In the puzzle discussed in "Mathematical Circus" (1992), two visible faces of one cube have digits 1 and 2 on them, and three visible faces