Thanks to you too Jix. I am familiar with Imperial and Metric measurements. I was born in UK in 1944 so was brought up and had my early adult life with Imperial. As a farmer who uses sprays and fertilisers I have had to contend with converting "Units" of fertiliser/acre to kgs/ha and ounces (dry and fluid)/acre to g or ml/ha. It becomes easy after a few years.
A slight problem with your gallons/litres conversion though. 1 US gallon = 3.785 litres. 1Imperial gallon = 4.546 - both rounded to 3 decimal places. I too still convert litres/km to mpg. Except for my tractor where I want to know litres/hour. I do a rare bit of contracting.
So far as I know, only the US deviated from Imperial measurements to their own pints and gallons. Other places either stuck with Imperial proper or never used it. The US also used a shorter weight measure for hundredweights and tons I think - 100lbs to a hundredweight instead of 112 and 2000 lbs to the ton instead of 2240. I note many figures in the agricultural US reports talking about millions of pounds so maybe the US ton was never really used much? A metric tonne (1000kgs) is 2205 pounds. Oh, and a pint of pure water weighs a pound and a quarter - except in the US where it is claimed "A pint is a pound the world around".
I also learned about bushels, pecks, quarters, chains, furlongs, rods, roods, poles and perches when I was at school. Forgotten a lot of it now, except that I used to have a chain measure (100links in a chain) and a cricket pitch is a chain long. Ten chains in a furlong, 8 furlongs in a mile. I am beginning to remember a few more now too. Hope you are right about it keeping away Alzheimers.
Edit: There apears to be a slight problem with duplicate postings recently. It happened with this one too. I definitely only clicked once as I am sure others have done too.