The square root of 27 is 5.19615242271. The number 27 is not a perfect square, so it does not have an exact square root. Numbers such as 36, 49 and 121 are perfect squares and have exact square roots.
The square root of a number can be a positive number or a negative number. For instance, the square root of 25 is 5 or -5; this is because the square of a negative number is a positive number. The square of -5 is written as (-5) x (-5), and this gives 25. Similarly, the square of 5 is written as 5 x 5 and this also gives 25. Numbers that are not perfect squares such as 22, 30, 45 and 50 have their square roots as a decimal fraction.