> Have you ever gotten 100% of the peanut butter out of a jar?
Peanut butter? No. I've gotten really close to 100% out of most containers of liquid though.
The exact location of the line between them might be hard to pin down, but when comparing things as dissimilar as that, it's a great big fat line so the overlap of where you put it and where it should be is probably pretty large, making it easy to place with some confidence.