Hard to predict because things happen so quickly okay and you can have things like this that go on okay but this is a much better indicator of what's about happen when either how big the number actually is or how quickly it's changing okay you want to know about the change in the change okay so in science that's the same thing almost every physical process Involves the amount itself, the change in the amount and the change on the change and all out derivative is, okay is the mathematical way to do those. 