While simplifying a term into simplest radical form you must take the perfect square out of the square root. Here are some simple perfect squares to just know on the top of your head 1^2=1, 2^2=4, 3^2=9, 4^2=16, 5^2=25 and so on... With 16 already being a perfect square then you can get the square root of it which would be 4. With that done, you would multiply the square root of 16 (which is 4) by 5 and would leave you with 20.
