What is the circumference of a 72" diameter circle? There is an amazing fact about circles that makes it possible to answer your question. If you have any circle, measure its circumference and diamater exactly, and divide the circumference by the diameter, the answer is always the same. It doesn't matter how large or small the circle, the circumference divided by the diameter is the number we call pi. Pi is approximately 3.1416 and hence Penny
