Final answer:
The square root of 81 is 9, which is classified as Natural, Whole, Integer, and Rational since it fits the criteria for each of these number sets.
Step-by-step explanation:
The classifications for ∙81 (the square root of 81) are multiple since 81 is a perfect square. When we take the square root of 81, we get the number 9, which falls into several different numeric categories:
- Natural: the counting numbers starting from 1, which includes 9.
- Whole: all of the natural numbers plus 0, which also includes 9.
- Integer: all of the whole numbers and their negatives, which also includes 9.
- Rational: any number that can be expressed as a fraction of two integers, and since 9 can be expressed as 9/1, it is rational.
Therefore, the correct classifications for ∙81 are Natural, Whole, Integer, and Rational.