Cube (algebra) however, easy to show that most numbers are not perfect cubes because "all" perfect cubes must have digital root 1, 8 or 9. That is their values modulo 9 may be only −1, 1 and 0. Moreover, the digital root of any number's cube can be determined by the remainder the number gives when divided by 3: Every positive integer can be written as the sum of nine (or fewer) positive cubes. This upper limit of nine cubes cannot be reduced because, for example, 23 cannot be written as the sum of fewer than nine positive cubes: The equation has
Cube 2: Sauerbraten episodic gameplay and deathmatches on multiplayer maps with AI bots instead of human opponents. Cube 2: Sauerbraten started as a redesign of the original "Cube" game engine. The "Cube 2: Sauerbraten" engine is written in C++ and OpenGL. "Cube 2: Sauerbraten" shares most of its design goals and philosophy with its predecessor, but using a new 6-directional heightfield (or octree) world model. Its first, developer-only, release was made on February 27, 2004. One of the latest releases, dubbed the "Justice Edition", debuted on July 19, 2010, adding two new player models, thirty new user-created maps, several new game modes, including