Right, I'm just saying I think it's reasonable to expect + to be kind of isomorphic with different representations of the same thing. Let's say f(x) gives some

Right, I'm just saying I think it's reasonable to expect + to be kind of isomorphic with different representations of the same thing. Let's say f(x) gives some alternate representation of x. Then f(3) + f(1) should be equal to f(3 + 1). Under this interpretation, f(3%) = 3/100 etc, so that 3% + 1% = 4%. But you could certainly argue that the idea of equating 3% with 3/100 is simply wrong. I like it because I like to think of "per" as meaning "divided by", and we generally use it that way when we use units like "metres per second = m/s = ms^(-1)".