1. Why do we need natural numbers?

Because we need to count things.

2. Why do we need whole numbers?

We need number where we can show that someone owes something.

3. Why do we need fractions?

Because we need a number to show how many parts od whole thing is taken/eaten.

4. Why so we irrational numbers?

So we can calculate area of round things.

5. Why do we need real numbers?

See 3rd and 4th answer.

6. Why do we need lateral (imaginary) numbers?

Because we need it for our alternate current calculations.

If you like video idea than watch all the parts

https://youtube.com/watch?v=T647CGsuOVU