There is no answer to this question. For any number that you care to name, I can pick one that is halfway between your number and 450 - namely the average of your number and 450 or (450+your number)/2. Being halfway between your number and 450, it is clearly nearer to 450. And then, I can find another number that is closer to 450 than that number and so on, for ever.
This depends what you are rounding 450 to. If its to the nearest hundred it's 500. If it is to the nearest whole number or tens place then it is 450.
453.0
Anything from 450 to 549
You do nothing. 450 is already rounded to the nearest ten.
450
This depends what you are rounding 450 to. If its to the nearest hundred it's 500. If it is to the nearest whole number or tens place then it is 450.
One answer is 450
453.0
450
450 and above to the nearest 10 which is 460
500
450
It is already rounded to the nearest ten as 450
As is. It is already rounded to the nearest tens place.
450
450
450.0