I suggest that you first
get acquainted with the GMAT so you have an idea of the various sections on the exam as well as the question formats. Once you understand what the test encompasses, you should take a
GMAT practice exam from MBA.com. The results of that exam will give you a good idea of what to expect on the GMAT and provide you with a baseline GMAT score. I also welcome you to take my free
37 question quant diagnostic that will provide some more data about your current quant skills.
However, I want to stress that the results of one practice exam are not nearly robust enough to give you a detailed idea of your strengths and weaknesses. For instance, if you get an average rate question correct on your practice exam, that result does not necessarily indicate whether you can accurately solve all rate questions: e.g. converging rates, catch-up rates, roundtrip, catch up and pass, etc.
So after taking your practice test, make sure to find a study resource that allows for linear, targeted learning accompanied by rigorous practice. In other words, you want to master one topic before you move to the next. If you do not know which GMAT study resource to use, you can check out the course reviews on GMAT Club or
Beat The GMAT, both of which have thousands of verified reviews of different GMAT prep resources.
Feel free to reach out with any further questions and good luck!!