Combinatorics · Lesson
Factorial compresses the product of all positive integers from n down to 1. It is the natural language of complete orderings.
Prerequisites: Fundamental counting principle
Goal: Interpret n! as a descending product and use it to count complete orderings.
Change the data, observe how the number of cases changes, and use the lab to understand the counting structure you are using.
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Completed exercises: 0/5 · Correct on first attempt: 0
Write all factors in descending order: the ! symbol is not multiplication by a mysterious number.
Data / situation: Calculate 5! and connect the result to a line of 5 distinct objects.
ConceptStep separates what is required from what is recommended or useful as reinforcement. Only required prerequisites block your progress.
Relationships: solid line = required · dashed line = recommended · dotted line = reinforcement.