Question

Find the square roots of the following numbers by expressing each number as the product of primes:

$81$

Answer 1

Expressing the given number as the product of primes as:

$$\begin{gathered} 81=3\times 3\times 3\times 3 \\ \therefore \sqrt{81}=\sqrt{(3\times 3)\times (3\times 3)} \\ =3\times 3 \\ =9 \end{gathered}$$

Hence, the square root of $81$ is $9.$