Factorial Calculator (n!)
Enter a whole number to compute its factorial (n!), the product of all positive integers up to n. Results use exact big-number math, so even large factorials are precise.
How to calculate a factorial
- Enter a non-negative whole number.
- Read n! computed instantly with full precision.
- Copy the result, including very large numbers.
Examples
Factorial of 5
5
120
Factorial of 0
0
1
Frequently asked questions
What is a factorial?
The factorial of n, written n!, is the product of every positive integer from 1 to n. For example 5! = 5 x 4 x 3 x 2 x 1 = 120.
Why is 0! equal to 1?
By definition the empty product is 1, and 0! = 1 keeps formulas for combinations and permutations consistent.
Can it handle very large numbers?
Yes. The calculator uses big-integer arithmetic, so results stay exact even when they have hundreds of digits.
Why can't I take the factorial of a negative or decimal number?
The standard factorial is only defined for non-negative integers. Decimals and negatives need the gamma function instead, which this tool does not compute.
Is my input private?
Yes. Everything is calculated in your browser and nothing is uploaded.
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