In finding the root of a number, just multiply that number by itself to get it's square root.
Example: 9x9 is equal to 81. Then, the square root of 81 is 9.
While in cube root. Just multiply itself thrice.
Example: 3X3X3 is equal to 27. Then, the cube root of 27 is 3.
You can also use the formula, (number times number) in finding the root of a squared number and (number times number times number) in cube.