Casio FX82 calculator I bought in 1982 at the age of 15. Used it throughout school, my apprenticeship and work as a draughtsman. Don't use it much now but it still works
fx-82ESPLUS | Non programmable | scientific calculator | CASIO
Casio PT-82 | Keen On Keys
CASIO FX-82 SUPER FRACTION SCIENTIFIC CALCULATOR FOLDING CASE NEW BATTERY WORKS | eBay