Once we got into high school math your "work" was more about the formulas you used or the thought process than the actual arithmetic. With a slide rule it is hard to get much under +/- 10% tho. At least with the cheap one I had and you still had to get the decimal point in the right place. That was usually the weak part in my process. When I got in the Navy school, (65) they were still pencil and paper. I never used a slide rule again. A few years later a 4 banger calculator was under $100 and I got one. (~72)
