I've just bought a new calculator for the office - ok, it wasn't expensive but I do, kind of, expect it to be able to do basic maths. It's a small Casio and someone else has checked their Casio out with the same results. This thing would never pass a Maths O level (or whatever they are these days).....
Simple percentages: 4 + 25% or 4 + 75% - believe this piece of junk and the answers are 5.333333 and 16 respectively......