Tombolio

Random number generator

Set the range, then press “Generate”.

Enter a minimum and a maximum, choose how many numbers you want and press “Generate”: you get a random number, or a series of up to 1,000, in a split second.

Both limits are included and can be negative. The “No duplicates” option guarantees that every number is different, and “Sort results” puts them in ascending order.

How to use it

  1. Enter the minimum and maximum. Both limits are included: from 1 to 6, the result can be 1 or 6.
  2. Choose how many numbers to generate, from 1 to 1,000.
  3. Tick “No duplicates” if each number should appear only once, and “Sort results” to get them in ascending order.
  4. Press “Generate”, then copy the result or the share link, which keeps your settings.

Ways to use it

  • Pick a winning number

    Do participants have an entry or ticket number? Generate a number between the first and last numbers handed out.

  • Create math worksheets

    Generate twenty numbers between -50 and 50 to put together a fresh addition or subtraction worksheet in seconds.

  • Build a random sample

    To audit a few files out of 2,400, generate 30 unique numbers between 1 and 2,400 and sort them so they’re easy to find.

  • Roll virtual dice

    Set the minimum to 1, the maximum to 6 and the quantity to 3 to roll three dice at once; switch to 20 for a role-playing die.

  • Choose a page or a question

    A number between 1 and the number of pages in the textbook or questions on the review sheet, and the session can begin.

How the randomness is guaranteed

Each number comes from your browser’s cryptographic generator (crypto.getRandomValues), which is designed to be unpredictable, unlike Math.random.

To bring that randomness into your range, the method throws away values that would create modulo bias (rejection sampling): every whole number in the range has exactly the same probability.

With “No duplicates”, a number that has already come up can’t be drawn again, and each remaining number keeps the same probability. All calculations happen in your browser.

Frequently asked questions

Are the limits included?

Yes. With a minimum of 1 and a maximum of 100, the generator can return 1, 100 or any whole number in between.

Can I generate negative numbers?

Yes. The minimum and maximum can be negative, for example -10 to 10. The maximum just has to be greater than or equal to the minimum.

Does the generator give decimals?

No, whole numbers only. To get a random digit from 0 to 9, simply set the minimum to 0 and the maximum to 9.

How many numbers can I generate at once?

From 1 to 1,000. With “No duplicates” on, the quantity can’t exceed the number of possible values: between 1 and 10, ten numbers at most.

Are these numbers truly random?

They come from the browser’s cryptographic generator, the one also used to create encryption keys. Its output can’t be predicted, and no whole number in the range is favored.

Can I use this generator for an official draw?

You can use it to choose between participants, as long as you follow your own rules. Tombolio provides the tool and does not run draws on anyone’s behalf.

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