Mental computation is the most common form of computation used in everyday life. It is used for quick calculations and estimations. Mental computation refers to the process of working out and obtaining exact or approximate answers mentally. The mental computation, with its significant educational challenges including the formation of future spontaneous citizen and able to participate in a debate of great scope, is a set of operations done mentally without intervention of a calculator, with a possibility to resort to the written supports. Several methods of mental multiplication have been elaborated. When calculating mentally, students select from a range of strategies, depending on the numbers used. In this article, we propose a new procedure of mental computation of two whole factors multiplication based on a schematic representation and a wise choice of simple or double reference.

Keywords : Mental computation, schematic representation, mental multiplication, IRM.