The worst thing is that for some, this is not a joke.
I remember meeting a retired electrician and he was so proud to show me: (1) he had a calculator; (2) he had a list of equations inside his calculator case, something like this (Yep, it is still available on the Web):
I only saw 2 [very simple, very basic] equations, that I know by heart even though electricity is not my domain. I wanted to tell him that it was just the same two equations rearranged differently, but I could see the mathematical concept would just go over his head. Still, he was proudly - half-joking, half-serious - saying stuff like: "See, I'm almost an engineer!"