Okay, but what will you do when battery runs out?Yes it's true they could do math but it took way longer - and they were less precise as the people doing the math by hand made mistakes and there was no easy way to make sure they did it right
If you were a money lender having a calculator would go a long way - and if you went a bit further in the future you could work for architecture firms calculating angles etc
CHECK MATE SCIENCE BELIEVER!