VITON13 SCHOOL · Maths
Random number generator
Numbers, names, teams, dice and coins, drawn fairly by your browser’s cryptographic generator. Nothing is sent anywhere.
Press the button and the result appears here.
History
Your results will appear here.
The last 20 results, kept only in this browser.
How to use it
- Choose a modeNumbers for a range, List to draw names, Teams to split a group, Dice or Coin for games.
- Set the rulesMin and max, how many, no repeats, sorting, decimals — or tap a preset such as 1–100 or 6 of 49.
- Generate and copyPress the button, copy the result in one tap and find your last 20 results in the history.
How fair is it?
Every value comes from crypto.getRandomValues, the cryptographically secure random generator built into your browser, not from the simpler Math.random.
Turning random bits into a number from a range can favour some values when the range does not divide the possible draws evenly. The generator avoids this with rejection sampling: a draw from the uneven top band is thrown away and drawn again, so every whole number in your range has exactly the same chance.
With “No repeats” numbers are drawn like balls from a drum: once a number is out, it leaves the pool. Teams are made by shuffling the whole list and dealing it out like cards, so team sizes differ by one at most.
Questions
Is this random number generator truly random?
It uses your browser’s cryptographic generator (crypto.getRandomValues), which is seeded with randomness from your device and is built so that its output cannot be predicted. Rejection sampling then makes every value in your range equally likely.
How do I pick numbers without repeats?
Turn on “No repeats”. Each number can then come up only once, as in a lottery draw. If you ask for more numbers than the range holds, for example 6 different numbers from 1 to 5, the generator tells you.
Can I pick a random name or split a class into teams?
Yes. Paste the names one per line. List mode draws one or more winners with no repeats; Teams mode splits everyone into a set number of teams or into teams of a set size, and the teams come out balanced.
Are my numbers and lists saved or sent anywhere?
Everything runs in your browser. Your last 20 results are kept in this browser only, so they are still there after a reload, and Clear removes them. Nothing is uploaded.
Sources
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