Casio fx-82super calculator

Quite old scientific calculator, according to https://www.calculator.org/calculators/Casio_fx-82SUPER.html both introduced and discontinued in in 1989.

One issue important for me is a lack of hexadecimal mode.

 Easy to open - 4 screws and latches places near battery compartment.

Looks like original cells, with expiry date of 1997. Not a sign of leakage and still full nominal output voltage.