in a kaplan example, they give a Ka problem where the gist is this:

Ka = [x][x] = 1.8 x 10^-5
[2.0]

and they get x to = 6.0 x 10^-3

so if you get x^2 = 3.6 x 10^-5, what's an easy way to find the square root of this to get x?

I would work with the scientific notation given......3.6 E -5 can be written as 36 E-6.....thus the square root would be easy....6 E-3