Question: if the circumference of a circle is doubled what is the area?
Answer: So when you double the radius, the area goes up by 4 times because 2 squared is 4. The area will always go up by the square of how much the radius goes up. By contrast, the circumference will only double -- from 12.56 to 25.12 because you do not square the radius (or diameter) -- you just multiply it by pi.