Leo: "I'm pretty sure pi is, uh, 3.1415 blah blah blah. The number goes on forever, but the sphere has only five rings, so that should be enough, if I'm right."
Frank: "And if you're wrong?"
Leo: "Well, then Leo fall down, go boom. Let's find out!"
The Mark of Athena - Rick Riordan

The Mark of Athena by Rick Riordan