Friendly Calculator...

I’ve forgotten how to turn it into a proper calculator…

While I was clearing a path for the plumber in our untidy garage I came across the above. I used to keep it in my office at work, in case anyone ever asked if I had a calculator they could borrow. It looks completely normal until you try to use it to do sums, at which point it displays one of a range of different insults. Snag is that in the days of spreadsheets and smartphones nobody ever asked to use it..