In This Chapter
Finding out how numbers were invented
Looking at a few familiar number sequences
Examining the number line
Understanding four important sets of numbers
One useful characteristic about numbers is that they're conceptual, which means that, in an important sense, they're all in your head. (This fact probably won't get you out of having to know about them, though — nice try!)
For example, you can picture three of anything: three cats, three baseballs, three cannibals, three planets. But just try to picture the concept of three all by itself, and you find it's impossible. Oh, sure, you can picture the numeral 3, but the threeness itself — much like love or beauty or honor — is beyond direct understanding. But when you understand the concept of three (or four, or a million), you have access to an incredibly powerful system for understanding the world: mathematics.
In this chapter, I give you a brief history of how numbers came into being. I discuss a few common number sequences and show you how these connect with simple math operations ...