Mmmmmmm.... Pi

From Richard Preston's new book Panic in Level 4:

"What is the point of computing pi... since an expansion of pi to only forty-seven decimal places would be sufficiently precise to inscribe a circle around the visible universe that doesn't deviate from perfect circularity by more than the distance across a single proton."

Preston's ability to put concepts like pi into terms that even a dolt like me can understand is why his books are so readable.