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
Casio fx-82 SOLAR FRACTION | IT History Society
CASIO FX 82 CE X (4549526602016) | MALL.SK
fx-82ES PLUS WE | SCHOOL & LAB. | Calculators | CASIO