I’ll probably have a number of questions, but my first is how to do calculations with units and Fixed-Point Maths. For instance, to find the slope of a line between two points:

To decide what real number is the slope of the line between/from (A - a thing) and/to (B - a thing):
decide on (y-coord of A - y-coord of B) / (x-coord of A - x-coord of B).

Where x-coord and y-coord are lengths (I’m using Metric Units, naturally). But this returns a number instead of a real number, so you get an error. You can’t use the Fixed-Point Maths calculations (real subtract, real divided by) because those can’t apparently handle units. And you can’t just get the answer as an integer and convert it to a real number, because it’s very likely a small fraction.