On a number line, let poin P represent the largest integer value that is greater than √201. Let point Q represent the largest integer value that is less than -√20. What is the distance between P and Q?

I think that you meant to write " the smallest integer value that is greater than √201 "

P = ceiling (√201) ≈ ceiling (14.177) = 15

Q = floor ( - √20 ) = floor ( -4.472 ) = -5

Distance between P and Q = P - Q = 15 - (-5) = 20 units