this paper, we generalize the study of the mathematical operations over (2x2), (3x3) and (4x4) real matrices by using the complex numbers which was introduced by (Ide. 1990,1993,1996), for any real matrices (nxm). This method of arithmetic operations of matrices by using the complex numbers and its properties is simple, easy and fast to program on computer. The importance of this method appears in the applications of problems which use the arithmetic operations of matrices, especially in physics.