### Theory:

Opposite numbers are two numbers whose distance from the origin of the coordinate axis (to zero) is the same but differ by a sign.
Numbers $$1$$ and $$-1$$ are opposite numbers because they are equidistant from zero (one box or one unit).
These numbers differ by a sign, with only one number to the right of zero ($$1$$) and the other to the left of zero ($$-1$$).
The opposite numbers for $$-2$$ is $$2$$; $$-3$$ is $$3$$; $$-4$$ is $$4$$ and so on.

The number opposite to zero is zero.

Do not confuse opposite numbers with inverse numbers.
The inverse of a number is called a fraction.
The inverse of $\frac{a}{b}$ is $\frac{b}{a}$.
Example:
The inverse of number $\frac{2}{3}$ is $\frac{3}{2}$.
You can also determine the inverse of a negative number:

$\mathit{The}\phantom{\rule{0.147em}{0ex}}\mathit{inverse}\phantom{\rule{0.147em}{0ex}}\mathit{part}\phantom{\rule{0.147em}{0ex}}\mathit{of}\phantom{\rule{0.147em}{0ex}}-\frac{31}{10}\phantom{\rule{0.147em}{0ex}}\mathit{is}\phantom{\rule{0.147em}{0ex}}-\frac{10}{31}$

To get an inverse number, swap the denominator of the part with the numerator, the sign remains the same.