#35 Is it precisely because I'm bad at classroom lectures that I can perform super-fast mental arithmetic by using an imaginary abacus that isn't even there?

It was probably about two weeks ago. I watched a YouTube Short video. It was a mental arithmetic video from the Raiju Channel ...

The reason I can still do mental arithmetic despite not touching an abacus for over 40 years: Seeing numbers as 'groups of 5'

Since I was in junior high school, I haven't touched an abacus or practiced mental arithmetic for over 40 years.Even so, I ...