Number Primality Test
Quickly check if the given number is a prime. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Number Primality Test
- 1. Paste your numbers. Enter one number per line into the input pane, the values you want checked for whether they are prime.
- 2. Read the verdicts. Each line reports whether its number is prime or not, and non-primes come back with the smallest factor found, like 98 is not a prime (divisible by 2).
- 3. Check the full batch. Because every line is processed independently, you can test a whole list of candidates in one pass instead of checking primality one number at a time.
- 4. Copy the results. Copy the primality verdicts into a math worksheet, coding interview prep sheet or number theory script.
When to use Number Primality Test
Number Primality Test checks a whole list of numbers for primality at once and explains a factor when a number fails the test. Use this tool whenever you need a quick, reliable answer for whether one or many numbers are prime, without writing your own trial-division check.
- Checking homework answers for a number theory class. A student wants to verify their manual primality checks on a list of assigned numbers, comparing against the tool's verdicts and factor explanations before submitting the assignment.
- Preparing coding interview practice problems. Someone building a set of practice problems around primality testing algorithms wants known-correct answers for a batch of test numbers to validate their own implementation against.
- Filtering a list of candidate numbers. A puzzle designer has a shortlist of possible numbers for a prime-based puzzle and needs to quickly confirm which ones actually qualify before finalizing the puzzle design.
Examples
Test a few numbers
Input
97 98
Output
97 is a prime 98 is not a prime (divisible by 2)
About the Number Primality Test tool
Number Primality Test runs as plain JavaScript in your browser tab, with no server behind it. Quickly check if the given number is a prime. Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's Number Tools section, 194 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 Number Primality Test 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.