### Theory:

In the previous class, we learned about natural numbers.
Natural numbers are $$1$$, $$2$$, $$3$$,…. They are also called as positive numbers.
Have you ever heard about negative numbers?

Yes, we heard these numbers in day-to-day life.
Example:
1. The average temperature in the Antarctic Plateau is $-56.7\mathrm{°}C$.

2. Your account balance is $$-100$$ rupees.
Negative numbers are $$-1$$, $$-2$$, $$-3$$,…. They come below zero.
Now, let us define integers.
Integers are the set of positive and negative numbers, including zero. Usually, it is written as …, $$-3$$, $$-2$$, $$-1$$, $$0$$, $$1$$, $$2$$, $$3$$, ….
Let's see about the sign of integers.
The opposite of every positive number is the same number with a negative sign.
Example:
1. The opposite of $$5$$ is $$-5$$.

2. The opposite of $$10$$ is $$-10$$.

3. The opposite of $$-15$$ is $$15$$.
Important!
The opposite of $$0$$ is $$0$$. It is because zero is neither a positive nor a negative.