Factorial Calculator
Compute n! exactly with BigInt, trailing zeros, prime-factor breakdown and a Stirling approximation.
n! = 1×2×…×n, with 0! = 1 by definition. Trailing zeros come from factors of 10 = 2×5: count = ⌊n/5⌋ + ⌊n/25⌋ + ⌊n/125⌋ + …. Exact values use BigInt, so precision never breaks — display is truncated past 700 digits.
About Factorial Calculator
Compute n! exactly with BigInt, trailing zeros, prime-factor breakdown and a Stirling approximation.
Factorial Calculator applies the standard formula for this calculation and returns a clean, readable result — no spreadsheet setup or manual working required.
How to Use Factorial Calculator
- Enter your numbers in the input fields shown above.
- Choose any options (units, rounding, precision) if the tool offers them.
- The result updates automatically — no button needed.
- Copy the answer or reset the fields to start a new calculation.
Key Features
- Instant results with a clear, readable output format.
- Handles decimals, percentages and large numbers cleanly.
- Fast and private — every calculation runs on your device.
Frequently Asked Questions
What formula does Factorial Calculator use?
Factorial Calculator uses the standard, widely accepted formula for this calculation. Results are rounded only for display, so they are reliable for homework, planning and quick checks.
Is Factorial Calculator free to use?
Yes. Factorial Calculator is completely free with unlimited use — no account, download or payment required.
Is my data uploaded to a server?
No. Factorial Calculator runs entirely in your browser. Your inputs are never sent to our servers or stored anywhere.
Does Factorial Calculator work on mobile?
Yes. The interface is fully responsive and works in any modern browser on Android, iPhone, tablets and desktops.
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