It is: 500
The answer depends on the extent to which the number is to be rounded. To the nearest tenths it is 5.0 while to the nearest tens it is 0.
Any from 499.5 to 500.49
The closest whole number to 54.876 would be 55. This is because .876 is above .500. Anything that is .500 or higher gets rounded up.
The greatest whole number would be 499.
To the nearest whole number is is 478.
There is no single answer to that, as it depends on what basis you are rounding on, like to the nearest 10 or the nearest 100 or the nearest 500 etc.
The smallest whole number that can be rounded to 500 is 450.
Since your decimal is higher than .500 you round up to the next whole number, in this case it is 20.
The number is 550. It is rounded up to 600, whereas the next smaller number 549 is rounded down to 500.
489.612 rounded to the nearest whole number = 490