Convergence rate
Named by 3 essays across 2 fields — each of them below, with the objects they name alongside it.
Getting pi by dropping needles on the floor
Throw a needle at a lined floor enough times, count how often it crosses a line, and pi falls out. There is no circle anywhere in the experiment.
How long until every one turns up
Draw at random from six equally likely kinds until all six have appeared. The wait is not six draws, and it is not sixty; it is fourteen point seven, and the number is a harmonic sum wearing a hat.
The sum that fits in one square
Half, then a quarter, then an eighth, forever. Adding infinitely many things sounds like it should give infinity, and the picture that says otherwise is a square with a corner left uncut.
Named alongside it
The objects these essays reach for when they reach for this one.
ConvergenceHarmonic seriesApproximationBuffon's needleCollisionDissectionEstimator biasThe Euler–Mascheroni constantExpectationGeometric seriesIndependenceIntegral geometry