We can factor 120 as 4 × 30.
This is nice because 4 is a perfect square and the only one hiding inside our radicand. It wasn't doing a very good job, obviously, since we found it right away. Given this,
We can't simplify any more. 30 factors completely as
2 × 3 × 5
and no factor of 30 is a perfect square, so we're done. The nicest it ever looks is