My interest in number multiplication goes back to exploring algorithms for generating Mandelbrot plots, which can require billions of multiplication operations on arbitrary precision numbers (numbers with *lots and lots* of digits).

**Multiplying** two numbers — calculating their *product* — is computationally intense because of the intermediate Cartesian product. Multiplying two 12-digit numbers creates a 24-digit result (12+12), but it *also* has an intermediate stage involving **144** (12×12) single digit multiplications.

Recently I learned an intriguing Japanese *visual* multiplication method.