Mono Monday Challenge - Balance

It's a long while since I did a Mono Monday Challenge, so here goes.

This is a very old calculator of mine, which in the past I have used to balance the accounts for a variety of clubs/organisations that I belong to / have belonged to. I always seem to end up as treasurer for whatever I join. 
I wouldn't mind, but I have to balance accounts at work too, so it's a kind of busman's holiday - without the holiday. 
Thanks to TheAphid for hosting this week's challenge.