# MULTIPLICATION OF MATRICES-MS EXCEL

Addition and subtraction of matrices do not offer much difficulty to the student. Basically the operation follows the usual arithmetic operation. But multiplication of matrices is a different matter. It is quite difficult as some rules are to be followed. The difficulty of operation increases as the size of the matrices to be multiplied also increases.

MS Excel becomes a valuable tool in obtaining a solution for matrices multiplication. The program saves time and effort. For purpose of illustration, open the MS Excel and solve the following matrices;

EXAMPLE: Find the product of matrix AB.
If matrix A= 4           2         3
1            1         2
2           1          3
and matrix B =    2         4
1           0

1           2

Find AB.

Solution:
Highlight vacant cells for the product. The product
is a 3×2 size. Then move the cursor to the formula bar and put = sign.
Then at Formula heading, browse for function MMULT. Dialogue box
appears. On array 1, highlight data of matrix A. On array 2, highlight
data of matrix B. Then press F2. Then press Ctrl + Shift + Enter
simultaneously. Answer appears at the space provided for the product, as follows;

13          22
5           8
8           14

Below is a dialogue box as shown in the spreadsheet.

Dialogue box where you enter the matrix data.