Found my dad’s slide rule. I don’t even remember how to use one, but he could do anything on one that you could use a “slide rule pocket calculator” to do. He would take it to the grocery store in the days before there were unit prices on price tags, to find out whether the “large economy size” was actually more expensive. Other customers in the store would watch him and then make their choices based on his results.
@EileenKCarpenter heh--I inherited my DIL's slide rule, which came in a nifty leather holster. It baffles me.
My dad failed to be able to explain logarithms to me because he thought of them in terms of the slide rule. “Logarithms let you multiply by adding!” Which did not seem any easier to me, but on a slide rule, yeah, you just move the slide and you’ve multiplied.