BTW, I expect they has memorized all the conversion factors and they had no calculators. Rods and bushels are out of my realm of experience.
Are you familar with the common criticism implying that our grandparents were uneducated because *they only had an eighth grade education*? It's often used in a disaraging way implying that they didn't really have a clue about what was going on because all they got to was eigth grade, making them barely literate. I mean, if they are comparing it to an eighth grade education of TODAY, yes, it would be an insult. In those days, they really educated kids and what they knew by 8th, I doubt most twelfth graders today could even touch.
Interesting thing is, the Mennonites still teach much along those lines. I've seen and used some of their curriculum and it is way more advanced than what you get out of the public high schools.
They probably had slide rulers and/or logarithm tables. That's how I was taught in the hoary and remote antiquity.