Factorials
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State
The factorial n! multiplies the counting numbers from n down to 1, counting the orderings of n distinct objects; by convention, 0! = 1.
Show
4! = 4 · 3 · 2 · 1 = 24 — four choices for first place, three for second, the Multiplication Principle run to the floor.
Builds on
- Nothing — this is a starting point.
Unlocks
- Nothing yet depends on this.