A number line is drawn by choosing a starting position, usually 0, and marking off equal distances, called scale marks, from that point.

The point for zero is called the origin (graphed above).  Points to the left of zero represent negative numbers and points to the right of zero represent positive numbers.  The number zero is neither positive nor negative.

A number line can be used to order and/or compare real numbers.  Numbers to the right get larger and numbers to the left get smaller.

DO NOW:  Using a number line, graph the following set of numbers and order them from smallest to largest:

{ 0.75, -1.0, 4 ¹/₂ , -3.8 }

[answer]

A number line can be used to find the opposite of a number.  Two numbers are opposites if they lie equidistant from the origin and on either side of the origin.

Answer: Graphing and Ordering Real Numbers

Ordered Set:   { -3.8 , -1.0 , 0.75 , 4 ¹/₂ }