How to use Prime Number Checker

Prime Number Checker does one job instead of burying it in a general-purpose panel: check primality and list primes up to a limit. That focus is deliberate, because a calculator is most useful when it answers a question in a single screen.

When Prime Number Checker is the right tool

The value of a focused calculator is that the inputs are labelled and the intermediate steps are visible.

• Verify a number for a math assignment or puzzle.
• Generate a list of primes for a cryptography exercise.
• Explore factorization of composite numbers.
• Check large candidate numbers quickly and privately.

Getting a reliable result

Check the units and the base of your inputs first, since most wrong answers are correctly computed from the wrong numbers. Where a summary statistic is produced, look at the spread as well as the centre before quoting it.

• Use the list feature only when you need every prime, not just one check.
• Keep list limits reasonable to avoid a very long output.
• Remember 0, 1, and negative numbers are never prime.

Mistakes that waste time

• Assuming 1 is a prime number.
• Forgetting that even numbers other than 2 are never prime.
• Requesting a prime list for a number far beyond the cap.
• Expecting instant results for extremely large numbers.

Privacy and local processing

Every computation happens in the page, so personal figures and datasets are not transmitted anywhere.

Related tools and reading

Open Prime Number Checker to try it with your own input. Nearby utilities include Statistics Calculator and Age Calculator. For background, read Summary statistics without misleading yourself, and browse the Math and Finance Calculators collection for the rest of the cluster.