Compute nPr and nCr with n! and r!, using iterative products for large-number safety.. Permutation & Combination Calculator is a free online tool from the ToolsRift Math Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Enter the total n and the number chosen r, and the calculator returns both the permutations (nPr) and combinations (nCr).
Permutations (nPr) count ordered arrangements; combinations (nCr) count selections where order does not matter.
nPr = n! / (n−r)! and nCr = n! / (r!(n−r)!), where n is the total and r the number chosen.
It multiplies iteratively rather than computing huge factorials directly, avoiding overflow for large n.