Abstract: Apparatus is disclosed for a mathematical game between a coder and a hacker. A method is disclosed for playing a mathematical game between a coder and a hacker. Apparatus is disclosed for a mathematical game for at least two players. A method is disclosed for playing a mathematical game by at least two players. Apparatus is disclosed for a mathematical game played by at least two players. A method is disclosed for playing a mathematical game.

Abstract: An arrangement for abacus-like calculation comprises a basic element comprising a first region with an array of first cells forming the first region, wherein each first cell represents a visual marking as to an assignment of each first cell, a second region with an array of second cells forming the second region, wherein each second cell represents a visual marking as to an assignment of each second cell, at least one first indicator unit accessed to the first region, wherein the relative arrangement between the first indicator unit and the first region is changeable in order to indicate a selected first cell of the array of first cells, and at least one second indicator unit accessed to the second region, wherein the relative arrangement between the second indicator unit and the second region is changeable in order to indicate a selected second cell of the array of second cells, wherein the visually marked assignment is marked on the basic element or on the indicator unit.