TopToolAIPermutation & Combination Calculator
ⓘ About this tool
🔄 Last updated 21 Sep 2026
✓ Reviewed by TopToolAI Team
Works out nPr, nCr and n! for any n up to 300. Answers are exact, even when they run to hundreds of digits, and the versions with repetition are included.
How to use Permutation & Combination Calculator
Step-by-step guide to the boxes below. Open it only if you need help.
How to use Permutation & Combination Calculator
Step-by-step guide to the boxes below. Open it only if you need help.
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1
n (total items) Text
Up to 300.
Example: 10
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2
r (items chosen) Text
How many items you pick. It must not be more than n.
Example: 3
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3
Press “Calculate”
Click the button under the boxes. If something is missing or not valid, a short message tells you which box to fix.
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4
Read your result
Your answer appears under the button, with a short note in plain words where it helps. Change any box and press again to compare different numbers.
Permutation & Combination Calculator FAQs
Permutation or combination?
If the order matters (ABC is different from CBA) it is a permutation. If it does not, it is a combination.
Why is nCr smaller than nPr?
nPr counts every ordering of each group, while nCr counts each group once, so nCr = nPr ÷ r!.
What are the formulas for permutations and combinations?
Permutations: nPr = n! ÷ (n − r)!. Combinations: nCr = n! ÷ (r! × (n − r)!).
What is a factorial?
n! is the product of all whole numbers from 1 to n. For example, 5! = 120.
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