[reidacdc]

You might want to give this more thought -- on reading the piece, my take-away was, "this guy is a half-step away from inventing the slide rule".

IMO, what the slide rule does is replace the memorization of squares and roots, or of logarithms of digits. I've never used a slide rule professionally, but I've noodled around with a few (I inherited a fancy one from my grandfather), and it really forces you to think about scaling and precision in a way that's different from both calculator and pencil-and-paper arithmetic, and the idea of knowing how to do the mantissa, and then using logical rules to infer the order of magnitude, is central. I think that's the through-line of the article, too, or at least it seemed so to me.

[D4ckard]

Yes, I see what you mean. To me, doing those sorts of calculations by hand is just really fun. I agree with you about the importance of applying logical rules in this way. Thanks for this suggestion, maybe I'm going to add a paragraph about the slide rule as an afterthought later on :D