Factorial Calculator
How This Converter Works
Calculates n factorial for integer inputs. Zero and one return 1; because Number coercion is used, a blank or whitespace-only field also becomes zero and returns 1. Negative integers show the page message Input must be a positive number, and non-integers show Input is not an integer. The field is limited to two characters. Large results use JavaScript number arithmetic and can lose precision or overflow.
Formula or rule
n! = 1 * 2 * ... * n for integer n >= 1; 0! = 1
Example
- Input
- 5
- Calculation
- 1 * 2 * 3 * 4 * 5
- Result
- 120