I'm not anymore, but I used to be a research mathematician. I absolutely cannot remember how to do long division, though I was certainly competent at it at one point. I'm also terrible at mental arithmetic these days.
These things were still indispensable on my path to being a mathematician though, they just ceased to be relevant as abstraction increased.
These things were still indispensable on my path to being a mathematician though, they just ceased to be relevant as abstraction increased.