Pre-Algebra Review Topic
Using Signed Numbers to Represent Opposite Situations
Topic Index | Algebra Index | Regents Exam Prep Center

Positive and negative numbers can represent or describe
 many different situations which demonstrate the
concept of opposites:

bullet Numbers on a number line.
bullet Temperatures on a thermometer: Temperatures above zero degrees are positive (+10) and temperatures below zero degrees are negative (-10).
bullet Sports scores: If your favorite football team gained 4 yards during the big game, it could be represented by +4.   Should your team lose 4 yards, it could be represented by –4.
bullet Weight gain and loss: Sam gained 8 pounds while on a Caribbean cruise (+8), but lost the 8 pounds after he returned home (-8).
bullet Geography:  A location in Death Valley has an elevation of -282 feet (which is below sea level), while a location near Coffin Peak has an elevation of +282 feet (which is above seal level).
bullet Altitude: An airplane leaves the airport and climbs to an altitude (height) of 2500 feet (+2500). To land, the plane must lose 2500 feet of altitude (-2500).
bullet Profit and loss: A candy store lost $28,400 (-28,400) the first year of business but recovered the amount (+28,400) the second year.
bullet Recorded time: When referring to historical times, 2000 years BC (-2000) can be compared to 2000 years AD (+2000).
bullet Elevator movement: The elevator went up 15 floors
(+15), and then went down 15 floors (-15).