Calculate a Factorial
Quickly calculate factorials (n!). Runs entirely in your browser, so your data never leaves your device.
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Output
The result appears here as you type.
How to use Calculate a Factorial
- 1. Paste your numbers. Enter one non-negative integer per line in the input pane. Each line is treated as a separate value to calculate a factorial for, so you can batch several at once.
- 2. Read the calculation. The tool computes n! for each line by multiplying every integer from 1 up to n, handling large values exactly rather than rounding to a floating-point approximation.
- 3. Copy the results. Copy the list of factorials from the output pane, in the same order as your input, into a spreadsheet, script, or homework answer.
When to use Calculate a Factorial
Calculate a Factorial computes n! for one or more integers exactly, without the precision loss you get from a calculator or floating-point language once numbers get large. Use it for combinatorics, probability, or checking a homework answer.
- Counting permutations. A combinatorics problem asks how many ways to arrange 12 distinct books on a shelf, which is 12!. Type 12 and get the exact count instead of estimating.
- Verifying a probability formula. You are computing a binomial coefficient by hand that needs several factorials, like 10! and 7!, and want exact values before dividing them out for the final answer.
- Checking code output. A recursive factorial function you wrote returns a number for n = 20 and you want to confirm it matches the true value before trusting the rest of the program.
- Exploring how fast factorials grow. Pasting 5, 10, 15 and 20 on separate lines shows at a glance how dramatically the values explode, useful for teaching or building intuition about factorial growth.
Examples
Factorials of several numbers
Input
5 10
Output
5! = 120 10! = 3628800
About the Calculate a Factorial tool
Calculate a Factorial runs as plain JavaScript in your browser tab, with no server behind it. Quickly calculate factorials (n!). Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's Math Tools section, 234 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.
There is nothing to configure. Provide the input and the result appears on its own. A worked example further down the page shows exactly what the tool produces for a real input.
That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.
Frequently asked questions
Is Calculate a Factorial free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.