A Set of numbers a ij (called elements ) arranged in a rectangular array of m rows and n columns constitutes a matrix of orders m × n . For example, of the arrays the first is a matrix of two rows and three columns, i.e. of orders 2 × 3, the second is a square matrix of orders 3 × 3. From a square matrix of orders n × n we can form a determinant of order n . Thus from the above square matrix we can form the determinant of order 3