The square root of a number is a value that, when multiplied by itself, gives the original number. For example, the square root of 9 is 3, because 3 x 3 = 9. The symbol for the square root is "√". So, √9 = 3.
There are two types of square roots: the principal square root and the negative square root. The principal square root is the positive value that, when multiplied by itself, gives the original number. The negative square root is the negative value that, when multiplied by itself, gives the original number. For example, the square roots of 9 are 3 and -3, because both 3 x 3 = 9 and -3 x -3 = 9.
The square root of a number can be approximated using a calculator or can be found using mathematical techniques such as the Newton-Raphson method. The square root of a number can also be expressed as an irrational number, meaning that it cannot be expressed as a fraction of two integers. For example, the square root of 2 is an irrational number that cannot be expressed exactly as a fraction.