How is the spacing between the numbers determined? How the @%$# does it work? Is there a mathematical term for it?
Logrithmic, my dear Blipson!
If you had attended engineering school before the turn of the 70s, you would have been intimately familiar with the "straight one"! Come to think of it, I just happen to have a slide rule (or "slipstick") in my desk drawer, for those times when I need something to fondle for nostalgia's sake.
Ah, yes... I just found my Acu-Math No. 400, a relatively cheap, single-sided version (all plastic -- no teak or mahogany cores like some of the elegant models of yesteryear). The primary C and D scales for higher-accuracy multiplication and division, the "backwards" CI (Inverse) scale, the "folded" A and B scales for quicker work, the S scale for Sines, and I may have to play a bit before I remember what the K, L and T (Tangent?) scales do...
Turn off your calculator and try one out for a while!
P.S. They're no good for addition and subtraction!