In This Chapter
Identifying addition and seeing how it works
Taking a close look at subtraction
Carrying in addition
Borrowing in subtraction
Checking your work
Every career has its basics — fundamental techniques that are the starting points for every other technique. In carpentry, you begin by hammering a nail and making a simple cut with a saw. In cooking, you begin with simple recipes. Even in sports, such as boxing, baseball, and the martial arts, you start with a basic stance. In fact, no matter what you're doing, if you don't get the fundamentals right, you're pretty much assured of having problems later.
Math is the same way. The basics are addition and subtraction. They're just a step beyond counting and form the basis for all other math operations. Counting is well and good (see Chapter 3), but eventually you run out of fingers and toes. That is to say, eventually counting is tedious, and you must go on to addition and subtraction.
If you live in the rain forest (like, for example, the Nadëb of Nadahup, Brazil) and don't have any commerce, you may have no need to count, add, or subtract. Your number system doesn't have any specific numbers above one. The Nadëb use a "1-few-many" system.
Because you probably don't live in the rain forest, you should read this chapter. It's not one page long. It's not many pages long. It's a few pages long.
In this chapter, you review exactly what addition is and the parts of the addition ...