中學數學問題，什麽是...

Opposite Numbers are two numbers that have the same magnitude but are opposite in signs.

Facts about Opposite Numbers:
(1) When opposite numbers are added together, the sum is zero.
(+5) + (-5) = 0

(2) To find the opposite of a number, you just simply change the sign.
(+ becomes -; - become +; Keep the value)

(3) The absolute values of opposite numbers are the same.
| +5| = | -5| = 5

For example:
+ 7 and – 7 are the opposite numbers.

- 7 is the opposite number of + 7.
+ 7 is the opposite number of - 7.