Brand: CASIO
Model: HL-809
Type: Calculator
Picture: CASIO HL-809
Batteries: AA x 2
Lifetime: Introduced: 1981
Terminated: unknown
Notes: Plain household calculator. The "="-key adds the calculation's result to the calculator's memory, which can be read using the "MR"-key.

A screwdriver is required to replace the two batteries. Probably because such a calculator usually lasts less long than its batteries.