Well if it's not about what we are using now but what will teach a kid to know roughly how big some numbers are, we could always ban calculators in favor of sli

Well if it's not about what we are using now but what will teach a kid to know roughly how big some numbers are, we could always ban calculators in favor of slide rules. What I mean, I guess, is that calculators are by their nature supposed to eschew estimation for the sake of simplicity. Porting estimation back into them seems like a mistake.