For a less impractical but still mind-bending algorithm, see Strassen's algorithm for large matrix multiplication. https://www.geeksforgeeks.org/strassens-matr

For a less impractical but still mind-bending algorithm, see Strassen's algorithm for large matrix multiplication. https://www.geeksforgeeks.org/strassens-matrix-multiplication/ https://www.geeksforgeeks.org/strassens-matrix-multiplicatio... , see also https://youtube.com/watch?v=ORrM-aSNZUs https://youtube.com/watch?v=ORrM-aSNZUs