Factorial Calculator
Calculate the factorial of any number (n!). Also computes double factorial and subfactorial.
How to Use This Calculator
Enter your values in the fields above and click "Calculate" to get instant results. This factorial calculator provides accurate results with step-by-step explanations.
Formula
n! = n x (n-1) x (n-2) x ... x 2 x 1
Quick Examples
- 5! = 120
- 10! = 3,628,800
- 0! = 1
Frequently Asked Questions
What is a factorial?
A factorial (n!) is the product of all positive integers less than or equal to n. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.
Why is 0! equal to 1?
By convention and mathematical definition, 0! = 1. This is because the empty product (multiplying zero numbers) equals 1.