You can't convert a number with decimals (or a fraction) to a whole number, without losing precision. You can round it to the nearest number, or truncate it (just remove the decimals), but in any case, that won't be the same number (just the nearest integer, in case you choose to round it), so "2.8 as a whole number" really doesn't exist.
28 __ 4 rename as a mixed number or a whole number
Yes, but it is not a cube of a whole number.
28
It is 28
80.
28 is, itself, a whole number.
Yes, 28 is a whole number.
28 __ 4 rename as a mixed number or a whole number
28 is already a whole number and no further rounding is possible.
Yes, but it is not a cube of a whole number.
28
It is 28
27.81 rounded to the nearest whole number is 28.
27.5 rounded to the nearest whole number is 28.
28
80.
28 over 28 is 1. every time the numerator is the same number as the denominator it will always be a whole number.