The surface area of the top surface of the water in a circular swimming pool is about 206 square feet. Estimate the radius of the pool, to the nearest foot.
The radius is 8 feet rounded, because to get that you have to divide 206 by pi, and with that you get a little more than 64, and the square root of 64 is 8, and you do all this because the area of a circle is pi times the radius squared.