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Permutations & Combinations

nPr, nCr, factorials with exact BigInt math.

n (total items)

r (chosen items)

Permutations nPr

720

Combinations nCr

120

3628800

Formulas

nPr = n! / (n−r)! = 10! / 7! = 720
  (ordered arrangements of 3 from 10)

nCr = n! / (r!(n−r)!) = 120
  (unordered groups of 3 from 10)

Repeated permutations n^r = 1000
Repeated combinations C(n+r−1, r) = 220

Exact BigInt math — no precision loss even for huge values like 100P5.