Concept
Remainder
2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
One point's worth of information
A Taylor series claims that everything a function does, everywhere, is encoded in its behaviour at a single point. That claim is extraordinary, it is often true, and the cases where it fails are the interesting ones.
Numbers that wrap
A clock does arithmetic. It has finitely many numbers, addition never leaves it, and multiplication behaves entirely differently depending on one property of the size of the dial.
Named alongside it
The objects these essays reach for when they reach for this one.
Analytic functionConvergenceCyclic groupDerivativeFermats little theoremGreatest common divisorModular arithmeticOrderParityPeriodicityPolynomial approximationPrimes