1. The problem is to find the square root of a number, which means finding a value that, when multiplied by itself, gives the original number. 2. The formula for the square root of a number $x$ is $\sqrt{x}$. 3. Important rule: The square root of a positive number has two values: a positive and a negative root, but usually, we refer to the principal (positive) root. 4. For example, to find $\sqrt{16}$, we look for a number $y$ such that $y^2 = 16$. 5. Since $4^2 = 16$, $\sqrt{16} = 4$. 6. Therefore, the square root of 16 is 4.