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.
 

Ultimate Guide to the Math ACT

Although this book is no longer supported, you can:

Click here to download errata.

Click here to download cross-references to The Official ACT Prep Guide, 2016-2017 edition.

Click here to download cross-references to The Official ACT Prep Guide, 2018 edition.

A Guide to the Math SAT

Although this book is no longer supported, you can:

Click here to download errata.

Click here to download cross-references to official SAT practice tests 1 through 8 (these may be found in the Official SAT Study Guide, 2018 edition or on the College Board web site).

Ultimate Guide to the Math ACT, Second Edition

Click here to download errata.

Click here to download cross-references to the 4 official ACT practice tests found in The Official ACT Prep Guide 2018-2019. These same four tests are published in The Official ACT Prep Guide 2019-2020.