I was a Saturday girl in Woolworths on decimal da. I still bear the scars.
As a scientist of a certain age I learned to do everything in at least two systems of measurement. I was seldom confused but I certainly confused other people
Distance in miles (still in the UK - why?) but in km all over Europe and often elsewhere
Temperatures - cooking, medical, weather, lab work in Fahrenheit then Celsius; I read a murder mystery recently in which the young Norwegian pathologist working in London recorded cadaveric temperature in F to estimate time of death. Burst out laughing - she would never have owned a F thermometer, the author must have taken it from an old copy of Simpson.
Used to do a lot of dressmaking and soft furnishings in an awful muddle of inches and centimetres (it always fitted though)
Then in science I learned SI (Système Internationale) at school because we were in the Nuffield science pilot. Then at uni they still worked in cgs (centimetre, gram, second) never did grasp the whole ergs and dynes thing, and found most of my lab colleagues worked in a mess of cgs and mks (metre,kilogram, second which isn’t quite SI)
My parent were both pharmacists and started out with prescriptions written in medical Latin and apothecaries measure (drachms, minims, scruples etc). I can read the Latin (sort of) but the only unit I know offhand is that a medicine spoon (teaspoon) is 60 minims.