The order of a matrix is defined as:

If a matrix has $m$ rows and $n$ columns, its order is defined as $m\times n$ (read as '$m$ by $n$ ').The total number of elements in such a matrix is given by the product $mn$.Example: $\left[\begin{array}{ccc}1& -5& 89\end{array}\right]$ is of order $1\times 3$ because it has 1 row and 3 columns.