My advice to all of you is to count the folds of fabric - 2 folds = 1yd. That isn't exact, but it is a pretty close estimate to what's there.
If the bolt is to have 10 yds, there should be 20 folds - If there's only 18 or 19 folds, you won't have 10 yds....
It is hard to tell if there are more than one piece on a bolt sometimes, though.