FAQ: Watch App - Square root using x^(1/y)
When you press the root button and get the reverse of the "x to the y power" i.e. x^(1/y) ... just type in the root reverse power number - for regular square root it's just the number two (2). So sqrt(4) = 4^(1/2) == 2 and just as well then root(8;3) = 8^(1/3) == 2 also!
Happy rooting! :-)