I over heard the phrase 10% life left or something to that effect as a nurse was assessing my grandfather who is very close to deah... if there is such a thing as 10% life what do they mean when they say it?

Did you hear the entire sentence? I have never heard anyone make that statement on a professional level. The honest truth is that your grandfather will die when he gets good and ready to. Believe it or not, people who are dying have more control over the timing of their deaths than we really know. When his personal business is finished, when his fears are eased, and when he's tired of fighting, he will let go. I see it all the time. Don't worry about what the nurse said. It means nothing. Just let him know that you love him, and that he can go whenever he is ready. That is the kindest thing you can do for him. Best of luck.