I’m almost done this math book, but I feel like it hasn’t really helped, and want a better understanding of the concepts. Is getting the College Panda practice test worth it (heard it doesn’t prepare well) or would another review book be helpful? And please don’t just say Khan Academy. Suggestions would be appreciated 
I’m currently looking at that math book too, can you please elaborate more on how you found it helpful/unhelpful? I heard that for math, Richard Corn’s SAT math is pretty effective.
PWN the Sat Math Guide https://www.amazon.com/PWN-SAT-Guide-Mike-McClenathan/dp/1523963573/
Worked well for my son he scored 800 on both the Math SAT and the SAT 2 Math level 2 DD used the older version for the old SAT and had similar results.