Concept
Square numbers
2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
Every square is a stack of odd numbers
Add up the odd numbers in order and the running totals are 1, 4, 9, 16, 25. This is not a coincidence, and the reason fits in a single picture.
Completing the square, by completing a square
The step everybody is taught as an algebraic trick is a literal instruction about a literal square. There is a corner missing, its size is forced, and paying for it is the whole method.
Named alongside it
The objects these essays reach for when they reach for this one.
Algebra tilesAreaCompleting the squareCounting two waysDissectionGnomonImaginary unitQuadratic polynomialsRootsSymmetryTriangular numbersUniform acceleration