A whole number is any number which is without any decimal or fraction.
The question was to round off the nearest of 22.48.
Now the rule is that if the number left to decimal is 5 or more than 5, round of the number by adding 1 to the number right to the decimal. If the number left to decimal is 4 or less than 4 then round off number simply by removing all left to decimal.
Now in our question there was 4 left to decimal. So we apply the second rule and the rounded off number will be 22.
