I think there's an easier way. I've been trying this for some time, and I think there's a pattern.

125, factorized equals 5x5x5. So, the cube root of 125 is 5, right.?

81, factorized equals 9x9, which can be simplified into 3x3x3x3. The cube root, joining 3 numbers together, is 3x(square root of 3), right?

I just think this is a simplier way to do it, but correct me if I'm wrong.