# What is the square root of a number ? Definition and examples.

The square root of a number is one of two equal factors of that number.

For example, 13  × 13 = 169 and 13 is one of the two equal factors of 169. Therefore, 13 is the square root of 169.

More examples of square roots

The square root of 100 is 10 because 10  × 10 = 100

The square root of 121 is 11 because 11  × 11 = 121

The square root of 225 is 15 because 15  × 15 = 225

The square root of 361 is 19 because 19  × 19 = 361

The square root of 625 is 25 because 25  × 25 = 625

The square  root of a number can also be a negative number.

For example, the square root of 100 could also be -10 because -10  × -10 = 100

The square root of 121 could also be -11 because -11  × -11 = 121

The square root can also be a real number.

For example, the square root of 250 is 15.81 or -15.81 since 15.81 × 15.81 is closely equal to 250 and -15.81 × -15.81 is closely equal to 250.

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