Free · Number playground

Prime Number Checker for Kids

Check whether a whole number is prime and see every factor that divides it evenly.

  • Clear, kid-friendly steps
  • Private in your browser
  • No signup

Number playground

Try your own numbers

Change the numbers, then press the button to see a clear answer.

Whole numbers work best here.

Number report

97 is prime

Only 1 and the number divide it evenly.

197

Powered by Fermat.ts, an open-source library available under MIT.

Three simple steps

How to use it

  1. Type one number, two numbers, or a short list.
  2. Press the big button to see the answer and a plain explanation.
  3. Copy the result, then try a new example.

Private by default

Your words and choices stay in this browser tab. There are no accounts, uploads, ads, or trackers inside the tool. Close the tab and the working data is gone.