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Factorial Calculator
Max: 170 (due to JavaScript limits)
5!
120
Digits
3
Scientific
1.20e+2
Calculation
5 × 4 × 3 × 2 × 1 = 120
Common Factorials
3!6
4!24
5!120
6!720
7!5,040
10!3,628,800
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How to Use the Factorial Calculator
- Enter a non-negative integer
- Select factorial type (regular, double, or subfactorial)
- View the result and step-by-step calculation
Factorial Types
- n! - Product of 1 to n
- n!! - Double factorial (same parity only)
- !n - Subfactorial (derangements)
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Frequently Asked Questions
What is a factorial?
Factorial (n!) is the product of all positive integers up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.
What is 0 factorial?
0! equals 1 by definition. This makes combinatorial formulas work correctly.
Where are factorials used?
Factorials are used in permutations, combinations, probability, and series expansions in mathematics.
Why do factorials grow so fast?
Each factorial multiplies by a larger number. 10! = 3,628,800 and 20! has 19 digits!