8 is called
a square root of 64 because 8 x 8 = 64. But -8 is also a square
root of 64 as -8 x -8 = 64.

Every positive number has two square roots,
one positive and one negative.

841 let say has 29 and -29 as its square roots because 29
x 29 = 841 and -29 x -29 = 841.

In general m is called a square root of a number N if m x m = N,
and then it will always be true that -m is also a square root.

The Notation √N
can be used for the positive square root of a number.
Note that the positive square root of a number between 0 and 1 is
always bigger than that number. √0.1681,
for example, equals 0.41
which is bigger than 0.1681.