Answer
Rational numbers, integers, whole numbers, natural numbers.
Work Step by Step
The number $\sqrt {16}$ is equal to $4$ because $4^2=16$.
A natural number is a number in the set $\{1,2,3,4,…….\}$.
Therefore, $4$ and $\sqrt {16}$ are in the set of natural numbers.
The set of natural numbers is included in the sets of whole numbers, integers, and rational numbers as well. Therefore, $\sqrt {16}$ is included in all of these subsets of real numbers.
