Mathematics
Diophantine Approximation and Continued Fractions
Quick fact
The golden ratio φ ≈ 1.618 is, in a precise sense, the most difficult number to approximate by rationals: its continued fraction is the slowest to converge, and its convergents are the ratios of consecutive Fibonacci numbers.
Why this is interesting
You've probably been taught that π is approximately 22/7. But why is that a good approximation, and could there be an even better one with a smaller denominator?