How it works
Calculate the factorial of a non-negative integer (n!).
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?number=NumberNumber · Optional · Default: 5
Outputs
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resultResultText · Primary output
result contains the calculator’s complete rendered result area, including its visible result cards, tables, charts, and messages.
Calculate $n!$ for any non-negative integer
Description
The Factorial Calculator is a dedicated tool for finding the “factorial” of a non-negative integer ($n!$). A factorial is the product of all positive integers less than or equal to $n$. For example, $5! = 5 \times 4 \times 3 \times 2 \times 1 = 120$. This calculation is a cornerstone of combinatorics, used extensively to determine the number of ways items can be arranged or selected.
Inputs
- Number (n): A non-negative whole number (0, 1, 2, 3…).
Outputs
- Result ($n!$): The final product, formatted with thousands separators for readability.
Chart
- N/A: This tool provides a direct numeric product result.
“Good to Know”
- The Zero Rule: By mathematical definition, 0! is always equal to 1, not 0. This is essential for the formulas used in probability and statistics.
- Growth Rate: Factorials grow extremely fast—much faster than exponential growth. While $5!$ is only 120, $10!$ is over 3.6 million, and $170!$ is the largest size most browsers can calculate before reaching “Infinity.”
- Permutations: Use factorials to find out how many ways a group can be arranged. For instance, 5 people can stand in a line in $5!$ (120) different ways.
Examples
Example 1: Small Factorial
- Input: 5!
- Output: 120
Example 2: Medium Factorial
- Input: 10!
- Output: 3,628,800
Example 3: The Boundary Case
- Input: 0!
- Output: 1