Calcolatore Permutazioni
Calcola il numero di permutazioni possibili di un insieme di elementi.
P(n, r)
720
P(n, r) vs Total Items (n)
Formula
How to Calculate Permutations
Formula
P(n, r) = n! / (n - r)!
A permutation counts the number of ways to arrange r items chosen from n distinct items where order matters. For example, selecting a president, vice-president, and secretary from 10 people is a permutation problem because each position is different.
Esempio Risolto
How many ways can you arrange 3 books from a shelf of 10?
- 01P(10, 3) = 10! / (10 - 3)!
- 02= 10! / 7!
- 03= 10 * 9 * 8 = 720
- 04Compare with combinations: C(10,3) = 120 (order does not matter)
Domande Frequenti
What is the difference between permutation and combination?
Permutations count ordered arrangements (ABC is different from BAC), while combinations count unordered selections (ABC and BAC are the same group). P(n,r) = C(n,r) * r!.
What is P(n, n)?
P(n, n) = n!, which is the total number of ways to arrange all n items. For example, P(5,5) = 120.
Can r be larger than n?
No. You cannot choose more items than are available. P(n, r) is only defined for 0 <= r <= n.
Impara