### Theory:

Positive and negative integers
Numbers less than $$0$$, are called negative integers. Negative numbers can be a whole number or fraction, for example, $$-1$$, $$-2$$, $$-0.7$$, $-\frac{2}{3}$.
Numbers greater than $$0$$, are called positive integers. Positive numbers can be a whole number or fraction, for example, $$3$$, $$2$$, $$8$$, $1\frac{3}{17}$.
Important!
Note that the number $$0$$ is neither positive nor negative.

Positive numbers, negative numbers (integers and fractions) and zero are called rational numbers.

Here, the numbers can be in fractional form.

$\begin{array}{l}\frac{p}{q}\phantom{\rule{0.147em}{0ex}},\mathit{where}\phantom{\rule{0.147em}{0ex}}p,q\to \mathit{Integers}\phantom{\rule{0.147em}{0ex}}\mathit{and}\phantom{\rule{0.147em}{0ex}}q\ne 0\\ \phantom{\rule{1.029em}{0ex}}\end{array}$ Every day, we use negative numbers when it comes to air temperatures, like minus six degrees or $$6$$ degrees below zero.
That means that the thermometer is $$6$$ degrees down from zero.

Looking at the mercury thermometer, we can observe that $$0$$$\mathrm{°}$$$C$$ (zero degrees Celsius) is in the middle.

Upwards are the positive degrees ($$1$$, $$2$$, $$3$$, ...), usually denoted by red (hot).

Downwards are the negative degrees ($$-1$$, $$-2$$, $$-3$$...), usually denoted by blue(cold).
Similarly, the Number line works similar to the example as mentioned above.