The square root pf a number can be simplified only if the number is divisible by a perfect square (other than 1).
√
12
can be simplified because
12
is divisible by
4
-- a perfect square.
√
12
=
√
4
×
3
=
√
4
×
√
3
=
2
√
3
√
250
can be simplified because
250
is divisible by
25
√
250
=
√
25
×
10
=
√
25
×
√
10
=
5
√
10
But
6
is not divisible by a perfect square, so
√
6
cannt be simpified further.