5.2.2 Uses of Negative Numbers
Negative numbers are used in many other practical applications. Banks and other companies use negative numbers to represent overdrawn accounts or a debt. For example, if you had $50 in your account, but then withdrew $60, your account would be overdrawn by $10, and this might be recorded as −$10 or ($10)—parentheses are sometimes used to show a negative balance.
You may also have seen negative numbers on maps, where they are used to record the depth below sea level, or on video recording equipment, where negative numbers are sometimes used to indicate position. If you’re an avid golfer, or enjoy following the Master’s on television, you’ve probably noticed that the scores are often negative (which is a good thing), representing the number of strokes below the average.
Negative numbers can be identified on the number line in a similar way to the temperatures on a thermometer. For example, the number line below shows the numbers −0.5, −1.8, and −2.4. These numbers could be read as “negative zero point five, negative one point eight, and negative two point four”.
[ Remember that the numbers increase to the right, so −1 is greater than −3 because it is to the right of −3. ]