Retro #9: Pocket Calculator

Came across this beast of a machine at work the other day. Made a speacial effort to continue with my Retro series. So much for the term Pocket Calculator !
I was a bit disappointed in myself because I couldn't work out it's operation, but managed to spell 819 80085* on the display, in true school boy fashion.

*Big Boobs

The beast is Schubert Rastatt ADM calculator from Western Germany.
Modell DRV
Maschinen-Nr 162572

;-)