Final answer:
The statement is false because the set of whole numbers includes all natural numbers and the number 0; therefore, a whole number could be the number 0, which is not a natural number.
Step-by-step explanation:
The statement "If a number isn't a natural number, then it isn't a whole number" is false. Natural numbers are a subset of whole numbers. Natural numbers include all positive integers starting from 1, 2, 3, and so on. Whole numbers, on the other hand, include all natural numbers plus the number 0. Therefore, if a number is not a natural number, it could still be a whole number if that number is 0.