As much as you would like to claim that there is a precise meaning to the phrase, the reality is that it is used inconsistently. I'm not sure how much clearer this can be, given the fact that it wasn't used according to the convention in this case. There is no need to be condescending to people, it isn't a matter of mathematical skill or language skill here. If you are really interested in shaming someone, the most you can say in this case is "they used the phrase inconsistently with convention!"

The moral of the story is that if you want to be precise, you should probably avoid the phrase altogether or include enough additional information to make it clear. Even if you are using it correctly, there are enough people out there using it incorrectly to give the reader some doubt, no matter how familiar with they are with English/math. As some others have pointed out, there are tons of ways to say it more clearly.

Let's try to keep these forums a positive place, and if we are going to argue, let's argue about something important like who would win in a fight between Merlwyb and Raubahn?