When I first created the Beginning Water Math Course, my goal with it was to be able to use it to pass your T2 and / or D2 exams. (If you are out of California, to gain an understanding of approximate level, California goes: Distribution 1-5, with 5 being the highest, and Treatment 1-5, with five also being the highest.) I still think it should be good enough for the D2. Having said that, some recent T2 exams have started to ask problems which I cover under the “Advanced Dosage” section of the Advanced Water Math Course. So If you want my completely honest opinion, I would say take them both if you are testing for anything greater than the bottom level exam. Know everything in the Beginning Course, and also be familiar with the first half of the Advanced Course.
There is a lot of crossover in the math. The entire Beginning Water Math Course, as well as the first half of the Advanced Course, are applicable to exams centered around either Treatment or Distribution. Higher level distribution oriented exams will need the material in the second half of the Advanced Course. People testing for a top level treatment centered exam will also need to know math problems related to preparation of aliquot solutions. Because they are only on top level treatment exams, I do not cover those in the math courses.
Also, make sure and check out the bonus math videos on the YouTube tab of this site.