Math warm-ups
Draw two numbers from 1–10 and have the class add, multiply or compare them. Spin the multiplication wheel for times tables.
Fair draws, shown big
Random Number Generator
Generate random numbers in any range, like 1–10, 1–30 or 1–100. Draw one or many, with or without repeats, and show them big on the board.
- No sign-up
- Cryptographic randomness
- Projector ready, no ads there
Range
1 to 100
Quick ranges
How many
Repeats
Sort from smallestShow several numbers in order.
SoundsTicks and a finish in this theme's voice.
Instant resultSkip the rolling numbers.
No repeats remembers what you've drawn, like a raffle drum, until you start over.
Numbers are drawn in your browser. Nothing is sent to ChalkSpin.
On the board
Every number in the range is equally likely
Ready when you are
?
Draws · 0
How it works
How to generate random numbers
- Set the range
Tap 1–10, 1–30 or 1–100, or type the lowest and highest numbers you want.
- Choose how many
Draw one number or up to 1,000 at once, with or without repeats.
- Press Draw or the Space bar
The numbers roll, then land big on the board. Each draw is added to the history with its time.
- Show it or copy it
Present puts giant numbers on the projector with no ads; Copy pastes them into a doc or spreadsheet.
Ideas for class
Ways to use random numbers
A fair number settles who goes first, which problem to solve and who wins the prize.
Student numbers
Give every student a number, then draw 1–30 with No repeats to call on them or line them up without saying names.
Raffles and door prizes
Set the range to your ticket numbers and draw one per prize. The raffle wheel shows the draw on a big wheel.
Pick a problem or a page
Draw a question number from the worksheet, or a page of the reader, so practice doesn't always start at number one.
Quick ranges
Popular ranges and what they're for
Every range works the same way; these are the ones teachers use most.
| Range | Good for |
|---|---|
| 1–6 | A dice roll for board games, probability experiments and partner games |
| 1–10 | Quick math warm-ups, number sense games and choosing a station |
| 1–30 | Student numbers in a class of up to 30, seat numbers or the day of the month |
| 1–100 | Hundreds-chart games, raffles, page numbers and estimation challenges |
How the randomness works
Each number comes from your browser’s crypto.getRandomValues(). Raw random values that would make some numbers slightly more likely are thrown away and drawn again (rejection sampling), so every number in your range has exactly the same chance.
Without repeats, the numbers still in the drum are shuffled with a Fisher–Yates shuffle and the first ones are drawn. With repeats allowed, every number is drawn on its own, so the same number can come up twice.
- Generator
- Web Crypto, in your browser
- Bias
- None: rejection sampling, no modulo bias
- No repeats
- Remembered until you start over
- Your draws
- Stay on this device
Questions teachers ask
Is a random number generator really random?
This one uses your browser's cryptographic random number generator (crypto.getRandomValues), the same source used for security keys, with rejection sampling so no number in the range is favoured. Every number from the lowest to the highest is equally likely on every draw, and nobody can set the result in advance.
How do I get random numbers from 1 to 100 with no repeats?
Tap the 1–100 range and keep No repeats on. Each draw skips the numbers already drawn, like pulling tickets from a drum, until all 100 are out or you press Start over. To draw them all at once in a random order, set How many to 100.
Can I draw more than one number at a time?
Yes. Set How many and press Draw. With No repeats the numbers are all different; with repeats allowed the same number can come up twice. Turn on Sort from smallest to list them in order.
Can I use it for a raffle?
Yes. Set the range to your ticket numbers, keep No repeats on and draw one number per prize. The draw history keeps the time and range of every draw. Raffle rules vary by state, so check yours; ChalkSpin only picks numbers and sells nothing.
Can I show the numbers big on the board?
Press Present or the F key for a full-screen view with giant numbers and no ads. Press Space to draw again and Esc to go back.
Can I use negative numbers or a big range?
Yes. Any whole numbers from −1,000,000,000 to 1,000,000,000 work, such as −10 to 10 for a number line or 1 to 1,000,000 for a big giveaway.