So you have a circle. What is the area of that circle? Surely everyone remembers that the area of a circle is: Where Pi (π ... the area density (mass per unit area) for the paper is fairly ...

Pi is the ratio of the circumference of a circle to its diameter ... In fact, Earth has a diameter of about 12,742km (7,926 miles) around the equator and 12,714km (7,900 miles) at the poles ...