Positive and negative numbers such as +3 and –5 are
called directed numbers because when represented on a number
line the direction in which they are measured from the origin
has to be taken into account.
numbers are met in everyday life as temperatures. 02C
is the origin: it is the freezing point of water. Negative
numbers such as –8 are used to indicate temperatures
below freezing, and positive numbers (usually with the + sign
omitted) indicated temperatures above freezing.