From Quora: My Answer to "What book should I buy to FULLY learn the math topics that appear on the SAT?"

Barron’s Educational Services has two books that would fill that bill. Barron’s SAT Premium Study Guide: 30th Edition has a very comprehensive section on the math problem “tricks” you will encounter on the SAT (Chapter 5), and how to counter them, as well as actual in-depth analysis of the underlying math (Ch. 6, which is split into 20 subchapters). This is a good choice if you don’t have a review book for the English sections, since it’s a comprehensive study guide.
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If all you need is a complete math review book, Barron’s also offers a math workbook, creatively titled Barron’s SAT Math Workbook, that is very detailed, and addresses practically any math problem that could be on the SAT. It’s up to the seventh edition, “for 2019 & 2020 tests.” If you can’t learn the math “fully” from those books, I suggest you supplement them with the excellent Khan Academy prep materials, available online for free. Here’s the link: Khan Academy