University of Utah
University of Utah: The Number System
This site from The University of Utah provides a definition of commonly used numbers including rational numbers, natural numbers, integers, real and complex numbers and more.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: High School Basic Algebra Review
An overview of basic high school algebra topics can be found here. Absolute value, signed numbers, inequalities and equations, mixture problems, and direct and indirect variation are all listed, each with links to questions posed by...
Curated OER
Math Words: Rational Numbers
Mathwords provides a brief description with an easy to read chart that includes all types of real numbers.