免费排列计算器
计算排列数P(n,r)，确定有序选取方案的总数。
Permutations
720
N Factorial3,628,800
N Minus R Factorial5,040
公式
## How to Calculate Permutations ### Formula **P(n, r) = n! / (n - r)!** Where: - **n** = total number of items - **r** = number of items being chosen - **!** = factorial Permutations count arrangements where **order matters**.
计算示例
How many ways can you arrange 3 items from a set of 10? (Order matters)
- 01P(10, 3) = 10! / (10-3)!
- 02= 10! / 7!
- 03= 10 × 9 × 8
- 04= 720
常见问题
What is a permutation?
A permutation is an arrangement of objects where the order matters. For example, the arrangements ABC and BAC are different permutations.
What is the difference between permutation and combination?
Permutations count arrangements where order matters (ABC ≠ BAC). Combinations count selections where order does not matter (ABC = BAC).
学习