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Module · Math · Statistics
Permutation & Combination
nPr (permutations, order matters) and nCr (combinations, order doesn't matter) with full factorial breakdown.
Permutations (nPr)
720
n! / (n − k)!
Combinations (nCr)
120
n! / (k!(n − k)!)
n! = 3,628,800 · k! = 6 · (n−k)! = 5,040
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Guide
How Permutation & Combination works
Step 01
Enter n and k
Total items (n) and how many to choose (k). k ≤ n.
Step 02
See both counts
nPr for ordered arrangements, nCr for unordered subsets.
Step 03
Factorial values shown
Verify by hand.
FAQ
Frequently asked
Difference between P and C?+
Permutations count order (ABC ≠ BCA). Combinations don't (both are the same set {A, B, C}).
Why max n = 170?+
171! exceeds JavaScript's Number.MAX_VALUE and returns Infinity.