It took a young kid quite some time in primary school to learn,(Was poor Gus in 1950)
Pound,shilling,pence,farthing.
Inch,foot,yard,furlong,mile,league.
Sq ft, sq yard,square mile,acre.
fluid ounce,cu.inches,cu.feet. cu. yard.
Ounce,pound,hundred weight,tons etc.
pound force,foot pound,pound foot.
Did Applied Thermodynamics in Imperial. Was fortunate I joined Ingersoll-Rand,USA and was using Imperial units for 32 years to quote air compressors,gas compressors and water pumps.
Took me some time to get use measuring in mm when machining. Found it convenient to use metric screws.Saved me all the trouble looking for nuts and bolts in BSW BSF BA NC NF etc. Not too many shops stock imperial fasteners. Also had a hard time using/reading metric micrometers.I am quite competent now.
I refuse to use metric dial gage. I am still with Imperial Dial Gages.Been aligning pump couplings with Imperial Dial Gage.
Actually the metric system is simple/easy to use compared to the 1/32 1/16 1/8 1/4 1/2 5/8
3/4 inch. They have no pound shilling pence farthing. No oz lb cwt ton .
After 40 years with Imperial , it was hard to go metric. We were bias.
Getting to like using Centrigrade.
Still very confused.