Yes we did use abacus in the early grades of primary school.
In Singapore it was usual to see abacus being used by small traders and hawkers, at least up to the 1990s. (Some may still do?)
Because I trust that most here are able to decide for themself if the post is relevant or not. If you find my posts irrelevant, feel free to jump to next post. I’m sure you will find something, somewhere that suites your taste.
I have noticed that you have been a pretty regular poster here. I wonder why?