Permutations (ordered selection without repetition) (P(n,r) = n!/(n-r)!: order matters, no repeat)
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P(n,r) = n!/(n-r)! — order matters, no repeat
What each symbol means
| Symbol | What it stands for |
|---|---|
| n | Distinct objects available |
| r | Positions / slots to fill |
| P(n,r) | Number of r-permutations from n |
When to use this
Integers with 0 ≤ r ≤ n. JEE: treat P(n,r)=0 if r>n when needed.