Below are errata and other supplemental materials for the books that are in print and are supported.

Regarding errata: books are written by humans and sometimes mistakes are made in spite of our best efforts. Any mistakes that are found are posted here as soon as they are verified.

Regarding cross-references: math topics in these books are cross referenced with the official study guides that were current at the time of the book’s release date. Cross-references may be updated when the official guides change substantially.
 

Math SAT: Improve your score by choosing the best tool

Click here to download errata.

Ultimate Guide to the Math ACT, Third Edition, Revised for the Enhanced ACT

Click here to download errata.

Ultimate Guide to the Math ACT, Second Edition

Although this edition is no longer supported, you can Click here to download errata.