I experienced this myself when I was a kid. I wanted to do mental arithmetic like my dad but I couldn't do multiplications for large numbers even after my dad e

I experienced this myself when I was a kid. I wanted to do mental arithmetic like my dad but I couldn't do multiplications for large numbers even after my dad explained how he did it. Turns out I had to memorize the time tables first, otherwise I would run out of swap space. If you want to experience this yourself but you already know the time tables, you could try to memorize log tables and then you can do those fancy arithmetic tricks that old school engineers used to do with slide rulers.