The basic idea about the reduction relating to an algorithm is that using the existing algorithm that solves the problem X (which is easy) can be also used to solve the problem Y (which will be harder to solve). It is widely known that multiplication of two matrices is relatively easy when those two matrices have the same dimensions (i.e., the square matrices: NN ). Explain then how you can use this multiplication of two same-sized (the square) matrices for multiplying two different size matrices (the rectangle matrices: MN ). There is no one right answer to this question so you can be creative in your explanation