MathWorld provides a huge mathematics encyclopedia detailing the concepts of geometry, algebra, calculus, discrete math, number theory, and other math topics--complete with formulas, diagrams, examples, and references for thorough...

Learn how to count in binary using just your fingers and how this skill can help you in arithmetic. Includes a set of practice questions.

An exploration of the binary system using U.S. postal zip codes. Discover what numbers the long and short bars in a zip code represent in this one page activity from the NCTM Math Challenges for Families collection.

While our number system is based on the number 10, there are many other possible ways to organize a number system, which are explored here.

In Spanish. This site has two educational games with step by step instructions. It also has a biography of different computers pioneers and an explanation of the decimal and binary system.

At this website from Math2.org you will find tables with information about number words, meanings, and the symbols used to express them. At the very bottom there is also a Java Base Conversion Calculator.