The square roots of 36 are 6 and -6. The square root of a number is a number that, when multiplied by itself, results in the original number. A number that is the square of a whole number, such as 36, is called a perfect square.

The symbol used to indicate "square root" resembles a checkmark and is known as a radical. When this symbol is used, the result is always positive. However, since two negative numbers multiplied together results in a positive number, the square root of 36 can also be -6. Other common square roots are: