Further Reading

Links 

All About Circuits - Numeration Systems

Arduino - Integer Constants

Sparkfun Tutorials - Transistors

Sparkfun Tutorials - Digital Logic

Also, if you're interested in playing around with digital logic and enjoying some Minecraft at the same time, Redstone circuits are a great way to learn and practice the basics. If you've ever seen videos of people building counters, adders, and mini-computers in Minecraft, binary math and basic digital logic are where they started.