Understanding Square Roots

We're asked to find the
square root of 100.

Let me write this down bigger.

So the square root is this
big check-looking thing.

The square root of 100.

When you see it like this,
this means the

positive square root.

If you're familiar with negative
numbers, you know

that there's also a negative
square root, but when you just

see this symbol, that means
the positive square root.

So let's think about what
this is saying.

This is asking us find the
number, the positive number,

that when I multiply that number
by itself, I get 100.

So what number when I multiply
it by itself do I get 100?

Well, let's see, if I multiply
9 by itself, that's

only going to be 81.

If I multiply 10 by itself,
that is 100.

So this is equal to-- and let
me write it this way.

Normally, you could
skip this step.

But you could write this as
the square root of-- and

instead of 100, 100 is the same
thing as 10 times 10.

And then you know, the square
root of something times

itself, that's just going
to be that something.

This is just equal to 10.

So the square root
of 100 is 10.

Or another way you could write,
I guess, this same

truth is that 10 squared, which
is equal to 10 times 10,

is equal to 100.