Factorial Calculator

Calculate factorials and permutations/combinations

n value (0–170)

Formula

Factorial: n! = n × (n−1) × (n−2) × ... × 2 × 1, where 0! = 1

Permutation: P(n, r) = n! / (n−r)! — ordered arrangements of r items from n

Combination: C(n, r) = P(n, r) / r! — unordered selections of r items from n

Actions:

How to Use

What is n factorial?

n! is the product of all positive integers from 1 to n. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.

What is the largest factorial it can calculate?

The tool can calculate exact factorials up to about 170!. Beyond that, results are shown in scientific notation.

What is the difference between permutations and combinations?

Permutations count arrangements where order matters. Combinations count selections where order does not matter.