The Division Rule: Counting Seats Around a Round Table | Discrete Mathematics §6.1

Sometimes you count the same arrangement several times without meaning to — like seatings around a round table that are really just rotations of each other. The division rule cleans up exactly that kind of overcount. In this video: the division rule, built on the board. When every outcome is counted the same number of times, divide by that count. We work the circular-seating example — why n people around a round table give (n−1)! distinct arrangements — then state the rule in its function form and see how it generalizes. This video is part of Discrete Mathematics · Counting (§6.1 — The Basics of Counting). Full section playlist → linked above / in the description on the channel. Made with the Engineering Simplified method: a calm, two-voice story lesson taught on a chalk-and-board, with every worked example written out step by step. Topic coverage follows Rosen, Discrete Mathematics and Its Applications (Chapter 6).