Permutation and Combination Calculator
Calculate permutation and combination using explicit client-side inputs.
Permutation and Combination Calculator Inputs
Results computed instantly — your data never leaves your device.
Live Permutation and Combination Calculator Results
Real-TimePermutations P(n,r)
720
Ordered selections without replacement.
How to Use the Permutation and Combination Calculator
- 1
Enter the population size n.
- 2
Enter the number of selected items r.
- 3
Review the ordered-selection result.
- 4
Confirm that r is not greater than n.
Formula & Mathematical Basis
Variable Key
nTotal items available
rItems selected in order
📝 This route reports permutations, where order matters; invalid r values return a guarded zero.
Step-by-Step Examples
Arrange three items from five
Scenario: Use n = 5 and r = 3.
- 1.Compute 5! = 120.
- 2.Compute (5−3)! = 2! = 2.
- 3.Divide 120 by 2.
- 4.Obtain 60 ordered arrangements.
Practical Use Cases
- Count ordered schedules or assignments.
- Compare ordered and unordered selection problems.
- Support introductory combinatorics exercises.
Common Pitfalls
- Using combinations when order matters.
- Entering r greater than n.
- Forgetting that factorials grow very quickly.
Frequently Asked Questions
Does this calculate combinations too?
No. It calculates P(n,r), where order matters.
What happens when r is zero?
There is one empty ordered selection mathematically; the production factorial formula returns 1.
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