First make an initial guess, then square the guess, and depending how close you got, improve your guess. Since this method involves squaring the guess (multiplying the number times itself)
For example: √20
first step is go by 2 as 20 is still a low number.
2 * 10 = 20
now see if 2 can go again into 10, yes it can so divide again by 2.
you get √(2*2*5) and the answer is 2√5
//Hope it helps