How is adding rational numbers different than adding whole numbers?

Answer 1

Whole numbers are rational numbers with a denominator of 1.

The difference with general rational numbers is that the denominators are likely to be different and they must be made the same by converting the fractions into equivalent fractions with the same denominator before the addition can be done - by adding the numerators and keeping the denominator, and simplifying (if possible) the result.

With whole numbers the denominators are already the same (as 1) and so the addition can be done straight away.

Answer 2

The main difference is that you must first convert the fractions to a common denominator, unless they already happen to have the same denominator.

Answer 3

Seeing that whole numbers ARE rational numbers,
there should be no difference expected.