Usually, shortly before the withdrawal deadline, and sometimes after, students ask me what their "current grade" is.
Here are several reasons why I do not provide this information in all cases except truly exceptional ones (see the end of bullet 3 below).

• The grade calculation, as per the syllabus, requires input from all tests, quizzes, Labs/Projects, etc.. By the withdrawal deadline, nor more than 60% of that information is available. Even a week before the final exam, some 20% of it is missing. Therefore, I simply do not know how to produce a number for the "current grade" with so much information missing. Whatever algorithm Blackboard uses for that purposes, must be some sort of extrapolation.
  

• I do not think that such extrapolation is any useful. Most students who ask for their current grade are in a precarious situation, where a small change in their overall numeric grade could be the difference between a pass and a fail, or between making and not making a GPA requirement for a scholarship. Any extrapolation is then intrinsically no better than a 50/50 guess: a small deviation from the extrapolated grade will result in drastic consequences for the student.
  

• As an instructor, I monitor your performance. I pay attention not so much to the grades themselves, but to your overall performance (which sometimes is a subjective concept that I base on my experience) and the dynamics of your grades. I do send out academic alerts (a.k.a. midterm warning letters) if I get concerned about a student. In those (fortunately) rare cases that I see that a student has a high chance of failing the course, I contact the student and request a meeting. At the meeting, I do provide my frank assessment of the situation and discuss possible scenarios. Sometimes I may have to compute - no, not the "current grade", - but the part of the grade that the student has already lost. I and the student can then estimate a portion of the grade that will be lost in the remainder of the course, and make a decision about staying in the course or withdrawing. 

• Finally, you are expected to keep all your work (quizzes, tests, Labs/Projects, etc.). Knowing the grades you have received so far and the final grade formula from the syllabus, you (being in a relatively advanced math course) should be able to do the aforementioned analysis of the number of points lost, yourself.
  

If you have any specific concerns after going through such an analysis, please contact me with its details and your questions.