If you have a number that is between 0 and 1, what would you call the number that you add to it to get 1? Is there a specific term for it? I was under the impression it had a name like inverse or reciprocal or something like that, although I know it is neither of those.
In probability, if the chances of something happening are 0.2, then 0.8 is the complementary probability, but I'm looking for a more general term.