Beginning Python®: Using Python 2.6 and Python 3.1

Chapter 2. Numbers and Operators

From our first breath of air, we are raised to use numbers. As a baby, we use them for estimating distance as we begin to crawl and, eventually, stand. As time progresses, we branch out and use them on a more conscious level, such as when we purchase a beverage or calculate our monthly budget. Whether you are one year old or 90, to some degree you are familiar with numbers. Indeed, numbers are such a familiar concept that you probably don't notice the many different ways in which you use them depending on their context.

In this chapter, you are re-introduced to numbers and some of the ways in which Python works with them, including basic arithmetic and special string format specifiers for its different types of numbers.

In this chapter you learn:

• To be familiar with the different basic categories of numbers that Python uses.

• To be familiar with the methods for using those numbers.

• The displaying and mixing the various number types.

Different Kinds of Numbers

If you have ever used a spreadsheet, you've noticed that the spreadsheet doesn't just look at numbers as numbers but as different kinds of numbers. Depending on how you've formatted a cell, the spreadsheet will have different ways of displaying the numbers. For instance, when you deal with money, your spreadsheet will show one dollar as 1.00. However, if you're keeping track of the miles you've traveled in your car, you'd probably only record the miles you've traveled in tenths of a mile, such as 10.2. ...