There's no reason for them, they just exist. It's like asking, what's the reason for the number 7 ? Prime numbers just happen to be numbers you can't divide by other numbers without getting fractions all over the place. Like 7.
it is bold
No reason why not.
No they don't, the reason they have numbers is because so people can remember them!
You have to add those two numbers then divide them by 2. The reason you divide by 2 is because they're two numbers.
No, not unless they have a good reason.
because 2 is prime
One reason that carbon atoms can form large numbers of compounds is that a carbon atom forms four bonds in its compounds.
Because the colour of a "negative wire casing" is black, hence the reason why negative numbers were written in this colour :)
The question has no sensible answer since it is based on a lack of understanding. All integers ARE rational numbers so there can be no reason why they are not!
What was the main reason that immigrants in citites became new voters in large numbers
Back in the dizzay, people would have old cashregisters that were big and for some reason they put the numbers on it staring from 9 and going to 0. There was not really a reason but it just stuck.