Factorial Calculator
Enter a non-negative whole number to calculate its factorial.
Formula
n! = n × (n−1) × (n−2) × ... × 1, with 0! = 1
Example
5! = 5 × 4 × 3 × 2 × 1 = 120.
Frequently Asked Questions
- Why is 0! equal to 1?
- By mathematical convention, the factorial of zero is defined as 1 — it represents the one way to arrange zero items.
Related Calculators
- Combination CalculatorCalculate the number of ways to choose r items from a set of n, where order doesn't matter.
- Permutation CalculatorCalculate the number of ways to arrange r items from a set of n, where order matters.
- Cube Root CalculatorCalculate the cube root of any number, including negative numbers.
- Exponent CalculatorCalculate a base number raised to any exponent.
- GCD CalculatorCalculate the greatest common divisor (GCD) of two numbers.
- LCM CalculatorCalculate the least common multiple (LCM) of two numbers.