The Wikipedia article on the “Irish logarithm” introduces an algorithm invented by Percy Ludgate for multiplying single-digit numbers. Instead of using a traditional multiplication table, Ludgate’s algorithm involves two separate tables called T1 and T2. T1 is used to look up the values of the input numbers, and T2 is used to find the product. The algorithm is specifically designed for mechanical computing engines, as the table lookups and simple addition can be easily carried out mechanically. Although Ludgate’s algorithm is not practical for manual calculation, it is an interesting solution for mechanical computation.
https://blog.plover.com/math/irish-logarithm.html