Concept
Natural logarithm
The power to which e must be raised to reach a given number.
Named by 2 essays across 2 fields — each of them below, with the objects they name alongside it.
The curve that is its own slope
There is exactly one shape of exponential curve whose steepness at every point equals its height at that point. The number that produces it is 2.71828…, and it was not chosen for elegance.
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.
Named alongside it
The objects these essays reach for when they reach for this one.
ApproximationCollisionCompound interestContinuityConvergence rateDerivativee, the numberThe Euler–Mascheroni constantExpectationHarmonic seriesLimitLinearity