2. Determining whether the two matrices can be multiplied The multiplication of two matrices is possible if and only if the number of columns in the left matrix is the same as the number of rows in the right matrix. If two matrices can be multiplied, then the number of rows of the product (matrix R) will be the same as the number of rows of the left matrix (matrix P). The number of columns of the product (matrix R) will be the same as the number of columns on the right matrix (matrix Q). See below.