To solve this you take the number being square rooted and divide it by the smallest number possible. As seen in the picture the number is divided by 2 down to 250 and again to 125. After that it no longer can be divided by two so now we go to 5's. When you get to one you're done. To get the answer circle pairs of two. There is a pair of 2's and a pair of 5's. So you multiply 2 by 5 to get 10 and the left over 5 stays in the square root.