I translate for engineering students from foreign countries, and I use this book to help me with my limited knowledge of Calculus, pre-Calculus, etc. I find all the "for Dummies" series very helpful.

The aim of this book is to introduce the subjects of pre-calculus in an easy, yet complete way. For the most part it accomplish it's objective, nevertheless, it has some typos and errors that will cause the student to get confused (i.e. the first time the student is shown the formula for the difference of cubes the book says something like this (a-b)(a^2+ab+b^3) which is wrong and in latter examples the formula takes the correct form of (a-b)(a^2+ab+b^2) which causes some confusion). Overall, this is a very good book specially for a review of the subjects.

UPDATE
P.105 Changing a Log's Base
log5/log3 does not equal ln3/ln5... it should read log5/log3 = ln5/ln3.

The aim of this book is to introduce the subjects of pre-calculus in an easy, yet complete way. For the most part it accomplish it's objective, nevertheless, it has some typos and errors that will cause the student to get confused (i.e. the first time the student is shown the formula for the difference of cubes the book says something like this (a-b)(a^2+ab+b^3) which is wrong and in latter examples the formula takes the correct form of (a-b)(a^2+ab+b^2) which causes some confusion). Overall, this is a very good book specially for a review of the subjects.