# What is the square root of 64?

##### 3 Answers

It's 8 or -8.

#### Explanation:

8 x 8 = 64.

The principal square root of

#sqrt(64) = 8#

The other (non-principal) square root is:

#-sqrt(64) = -8#

#### Explanation:

#8^2 = (-8)^2 = 64#

When we say "the square root", what is usually intended is "the principal square root", which in the case of the Real square root of a positive number is the positive one.

Any non-zero number

**Complex footnote**

If

#+-i sqrt(-n)#

In this case we call

For example:

#sqrt(-64) = 8i# is the principal square root.

#-sqrt(-64) = -8i# is the other square root.

Note that