If a sphere’s radius is quadrupled, what is the corresponding change in surface area?

The surface area of a sphere is four times the area of the largest circle that can be formed out of it. Mathematically, the surface area SA = 4πr^2. There is a direct variation between the surface area and radius. 

                                       SA = 4π(4r)^2

                                       SA = 64πr^2

Thus, the surface area is multiplied 16 times if the radius is quadrupled.