Suppose that a teacher says
I will minus your points if you cheat.
To mean “I will deduct your points.”
Here, minus is apparently used as a verb.
Checking out the dictionaries,
it can be seen that minus is only listed
as a preposition, adjective, and/or noun.
However, some people argue that “minus your points” is a phrase
Therefore, I ask this question here to double-check
that it is invalid to use “minus” as a verb.
Is this phrase acceptable?
If so, is it commonly used?
It is an unfortunate but not an uncommon use of the word. In environments where math is done and spoken of casually such corruptions are not unusual. They should have some of their points minused themselves.