C Programming
- Learn-C.org — an interactive tutorial (write and run code within the site) with pages for many commonly-encountered topics.
- C Tutorial — a short, simple tutorial on some basics of the C language.
Concepts
- The Binary Number System — a very quick explanation of how binary numbers work, including fractions. There's a slightly longer explanation from a different perspective here.
- And if you don't yet have common powers of two memorized, you'll want to work on that. Knowing at least 28, 216, and 232 off the top of your head will be very useful.