CASIO SCIENTIFIC CALCULATOR FX-82ES PLUS FX82 FX-82 FX82-ES PLUS 2nd EDITION | eBay
Casio fx-82MS - iFixit
Solution of Quadratic Equation with Scientific Calculator | CASIO fx-82MS - YouTube
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