Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Statistics, Probability & Advanced Math
How to Calculate Permutation and Combination
Instant math result
Permutations count ordered arrangements; combinations count unordered selections. Enter n and r to compute both fundamental counting values.
Inputs
0170
0170
Smart analysis
Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
n (total items)
The “n (total items)” value used in this tool’s formula. Adjust it to see results update live.
r (chosen items)
The “r (chosen items)” value used in this tool’s formula. Adjust it to see results update live.
- n
Set size
Total items.
- k
Chosen
Items selected.
When to use this Permutation and Combination
Common use cases
- Check homework results with transparent formulas
- Estimate probability for common distributions
- Convert between related statistical measures quickly
Localized examples
- Classroom and exam-prep workflows
- Business analytics back-of-envelope checks
What you get
- Formula-backed outputs with clear labels
- Step-friendly defaults for learning
- Free online calculator — no sign up
How to Calculate Permutation and Combination Step-by-Step
- 1Enter total items n.
- 2Enter items chosen r (r ≤ n).
- 3Review permutations and combinations.
Governing formula
P(n,k)=n!/(n−k)! · C(n,k)=n!/(k!(n−k)!)
Counts ordered arrangements (permutations) or unordered selections (combinations).
Example: set n (total items) = 10, r (chosen items) = 3, then read the result.
Variable definitions
- n
Set size
Total items.
- k
Chosen
Items selected.
- Requires integers with 0 ≤ k ≤ n.
Frequently Asked Questions
When order matters, such as rankings or sequences.
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Reviews & Ratings
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4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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