Wikijunior:Introduction to Mathematics
This Wikijunior book is designed to teach you, in less than a year, all of the mathematics you'll need to pass a lower level college.
Not everyone has the good fortune to be taught their numbers and letters before entering kindergarten, but everyone can learn to do math well.
This book begins at the beginning. It assumes you know how to read, nothing else. (If you have trouble reading this, you need to learn reading first, but you can work on math, too, if you have someone to read to you.)
The book is organized in a series of short lessons. Each lesson starts by saying what it is designed to teach. If you already know what that lesson is designed to teach, skip to the next lesson. Do not skip any lesson you are not absolutely certain you know. Every lesson builds on what has gone before.
If you want more instruction, especially gearing up for college, read More on Mathematics. It was made for the average reader to be able to understand it.