It's really not that hard. Here, I'll show you an example.
So you take the square root of 100 and see what two number can multiply to get 100.
You can multiply 10 and 10 to get 100.
Then you see what two numbers you can multiply to get 10. 2 and 5
2 5 2 5
Then you write out the number that you got from least to greastest.
Then since you have two 2's and two 5's you combine them to make them one 2 and one 5
You then take both of the numbers outside of the square root.
You then multiply then numbers and get your answer, which is 10.