No calculator needed assuming you can remember multiple intermediate variables or have the conversions memorized. It's a great "power user" system for skilled

No calculator needed assuming you can remember multiple intermediate variables or have the conversions memorized. It's a great "power user" system for skilled professionals in the pre computer age who practiced with it regularly, and it works well in things like woodworking where you still have a lot of things done on paper or just in someone's head. It's not the best for CAD first workflows, when you're trying to model everything down to where to clamp the edge guide blocks for the saw, and changing something without changing the model and confirming it will all fit isn't a thing. In 3D printing you get down to 0.4mm or occasionally even 0.2mm gaps between things, although none of it is really an exact science, and you assume some sanding may be needed to make things fit unless you have an amazing tuned printer. But I suppose woodworking is less of an issue, because you're probably not going to get even 1/16th precision by hand unless you're really skilled, in which case you probably have fractions memorized.