Terminated: unknown
First the very unusual battery compartment which isn’t at the back, but at the front of the calculator. The top orange part can be removed.
Secondly the rather unusual "currency" mode. When the "A/M" slider is set to "M", the calculator switches to two-decimal currency mode. In this mode, numbers are entered from the "cent" position and shifted to the left. To enter $0.05 simply type 5. To enter $0.15 type 1 5. To enter $1.23 type 1 2 3, etc...
The OMRON 86R’s shown here are the first and second revisions of the calculator. The first revision uses two LEDs to indicate negative and overflow, has no "A/M" slider and no +/- key.
The version with the blue √ key was donated to the museum by Nellie Tiemens, thanks Nellie!