### Chapter 2 - Numbers

Systems of equations are made up of equations, equations are made up of expressions,
and expressions are made up of numbers. So at the very bottom of the mathematics
food chain are numbers. In this chapter we look at the types of numbers, operations
on numbers and uses of numbers. This chapter contains the following sections:

- section 2.1 - In this section we talk about the
types of numbers, ranging from the natural numbers to the complex numbers.
We place each type on the number line.

- section 2.2 - We explain the addition and subtraction of positive and negative numbers using arrows placed end-to-end on the number line.

- section 2.3 - We explain the multiplication of positive and negative numbers in terms of stretching and reversing of arrows on the number line.

- section 2.4 - We explain the division of positive and negative numbers.

- section 2.5 - We introduce scientific notation as a way of representing very large or very small numbers.

- section 2.6 - We talk about approximate numbers, rounding and significant figures.