Rubik's family cubes of all sizes Rubik's family cubes of all sizes The original Rubik's cube was a mechanical 3×3×3 cube puzzle invented in 1974 by the Hungarian sculptor and professor of architecture Ernő Rubik. Extensions of the Rubik's cube have been around for a long time and come in both hardware and software forms. The major extension have been the availability of cubes of larger size and the availability of the more complex cubes with marked centres. The properties of Rubik’s family cubes of any size together with some special attention to software cubes is the main focus of this article. Many properties are mathematical
Balance puzzle Balance puzzle A balance puzzle or weighing puzzle is a logic puzzle about balancing items—often coins—to determine which holds a different value, by using balance scales a limited number of times. These differ from puzzles that assign weights to items, in that only the relative mass of these items is relevant. For example, in detecting a dissimilar coin in three weighings (n = 3), the maximum number of coins that can be analyzed is = 13. Note that with 3 weighs and 13 coins, it is not always possible to determine the identity of the last coin (whether it is