## Square roots

The root of a number y is another number, which when multiplied by itself a given number of times, equals y. The second root (also called the **square root**) of 16 is 4:

$$16=4×4$$

We write this as:
$$√16=4$$

or
$$√^2{16}=4$$

For every even-degree root (2nd, 4th, 6th ....) there are two roots. This is because multiplying two positive or two negative numbers both produce a positive result. E.g:

$$4×4=16$$

$$(−4)×(−4)=16$$

Thus, $√^2{16}=±4$

The value inside the symbol √(called **radical**) is called **radicand**.
For $√^3{64};;;$ 64 is radicand and 3 is the **index**.