Comment by pjc50

Now that's a properly dead skill, surely. I have my dad's one somewhere, and know roughly how it works, but I've not touched it this century.

I also have one of these: https://archive.org/details/spencersdecimalr0000unse ; I believe they were popular around the time of the UK converting to decimal currency, to save people having to do the transitional arithmetic. Had a bunch of other tables in. A physical LUT.

I wonder if there's anyone with abacus skills here. I hear that held out against calculators a lot longer, for shopkeeper uses.