I don't see how I'm contradicting the rules. It is a mathematical expression, which, when solved, gives you the number that I ended up at from the -19 before me. You could argue that it is not "reasonably understandable" to everyone, and I can counter that with "even if you don't know the math in question, there are tools that will solve the equation for you". Unless the image is not showing for you - I have no idea why it wouldn't, though, it's just linked from imgur. The number was -18, by the way. And now it is -18 again.