You take the number you are given, say 144, and you find a number that you can multiply by itself to get the number you are give. For 144 the square root of 144 is 12 because 12 times 12 is 144. And it is the same thing for the cube root of a number, you just find a number that can can be multiplied by itself 3 times to get a number, like 8, the cube root of 8 is 2, because 2 times 2 times 2 is 8.