The square root of 89 is 9.43. The square root of a number, y, is the number, x, that when multiplied by itself results in y, as in x times x equals y. For the number 89, 9.43 times 9.43 equals 89.
Sometimes, it is possible to simplify square roots by factoring out the square of a whole number. However, since 89 is a prime number, it is not possible to simplify it any further. The easiest way to determine the square root is to use the appropriate function on a calculator. Graphing calculators contain a square root function that is not always available on basic calculators.