Square root of some number a call such number b that b² = a. Square roots from small numbers can be calculated in mind, for example √16 = 4, √81 = 9, √169 = 13. If it is necessary to calculate a root from larger numbers, then the computer facilities, for example, the calculator come to the rescue. How to be if there is a task to calculate a square root, for example, of four-digit number, and there is no calculator near at hand? There is a method allowing to take a square root from natural number with any number of figures.

In many school and purely practical tasks it is required to calculate the cube root called also cubic root. Despite external simplicity of a task, it is not so simple to calculate a cube root. On calculators there is no button calculating this function.

The number which is under the sign of a root often disturbs the solution of the equation, it is inconvenient to work with it. Even if it is built in degree, fractionally or cannot be presented in the integer form to some extent, it is possible to try to bring him out of a root, completely or at least partially.

In mathematical tasks such expression as a root square of a square sometimes meets. As squaring and extraction of a square root – function the mutually return, some just "reduce" them, rejecting the sign of a root and square. However such simplification is not always correct and can result in incorrect results.