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Math

Factorial Calculator

Calculate the exact factorial of a whole number from zero to 500.

Exact method explained belowEditable inputs

Set up your calculation

Runs on your device

SOLUTION

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter whole number n.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

n! is the product of integers from 1 through n. By definition, 0! = 1. Results use arbitrary-precision integer arithmetic.

A WORKED EXAMPLE

5! = 5 × 4 × 3 × 2 × 1 = 120.

What to keep in mind

Only whole numbers from 0 to 500 are accepted. This does not extend factorials to non-integers through the gamma function.

Common questions

Why is zero factorial one?

The empty product is defined as one, making combinatorial identities consistent.

Are large results rounded?

No. The factorial is displayed as an exact integer; copy it to preserve every digit.

Methodology maintained by ClarityKit. How these tools are built and checked.