Infinite Powers: How Calculus Reveals the Secrets of the Universe

by Steven H. Strogatz

3 + 10 / 71 < π < 3 + 10 / 70. The unknown, and forever unknowable, value of π is trapped in a numerical vise, squeezed between two numbers that look almost identical except that the former has a denominator of 71 and the latter of 70.