Casio fx 31. Dad bought this during his college days in 1978. Running flawlessly since 41 years now. I use it sometimes when I'm bored of using my phone. : r/BuyItForLife
File:Casio DBC-32-1AES mit Resin Armband.jpg - Wikimedia Commons
Casio DBC-32-1ADF
Casio Taschenrechner FX 350 Ex: Amazon.de: Bürobedarf & Schreibwaren
Index of /Museum/Calculator/FX/FX-102
Casio DBC-32-1AES watch - Databank Calculator
CASIO fx-82SP X ClassWiz Iberia Wissenschaftlicher Taschenrechner, 13,8 x 77 x 165,5 mm, dunkles Schwarz : Amazon.de: Bürobedarf & Schreibwaren