Math
Permutations & Combinations
nPr and nCr for any n, k.
Result
120
Combinations C(10, 3)
Permutations P(n,k)
720
Combinations C(n,k)
120
Compute permutations P(n,k) and combinations C(n,k) using log-factorial to avoid overflow.
How it works
P(n,k) = n!/(n−k)!. C(n,k) = n!/(k!(n−k)!).
Example
n=10, k=3 → P=720, C=120.
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