How to roll virtual dice
Choose the number of dice and their sides before you roll. Six-sided dice show dots like physical dice; other dice show a number inside the die’s outline.
- Set How many to 1 to 12 dice, using One fewer or One more to adjust the count.
- Choose Sides from 4, 6, 8, 10, 12 or 20. For another size, choose Other and enter 2 to 100 in Number of sides.
- Select Roll or press Space or Enter. Read the individual results and the total shown after the roll.
- Open History to review the last 20 rolls. Turn on Count each face if you want to count how often each face appears.
- Select Full screen or press F to show only the tool on your projector. Press Esc to return to the page.
Odds for two six-sided dice
Two six-sided dice have 36 equally likely combinations, but their sums are not equally likely. The sum 7 has the most combinations; 2 and 12 have the fewest.
Use this table during a probability discussion to compare possible sums with your class’s recorded results. These are the computed probabilities for each roll, not a schedule of what must appear.
| Sum | Combinations | Probability |
|---|---|---|
| 2 | 1 of 36 | 2.78% |
| 3 | 2 of 36 | 5.56% |
| 4 | 3 of 36 | 8.33% |
| 5 | 4 of 36 | 11.11% |
| 6 | 5 of 36 | 13.89% |
| 7 | 6 of 36 | 16.67% |
| 8 | 5 of 36 | 13.89% |
| 9 | 4 of 36 | 11.11% |
| 10 | 3 of 36 | 8.33% |
| 11 | 2 of 36 | 5.56% |
| 12 | 1 of 36 | 2.78% |
Ways to use dice in class
Decide what each result means before you start, so the class can follow the same rule throughout the activity. Keep the dice on the projector for whole-class work, or use them on a classroom device at a center.
- Addition warm-up: roll two six-sided dice for the whole class. Have students work out the sum before checking the displayed total, and continue until the warm-up ends.
- Probability discussion: ask pairs to predict which sums will appear most often. Roll during the discussion, record the sums, and compare the results with the table.
- Small-group review: number your prepared prompts to match the die’s range. Roll to choose a prompt each turn, continuing until the group’s review time ends.
- Coin-flip exit ticket: flip a coin for the class and assign a different prompt to each possible result. Keep the result visible while students write their responses.
Common questions
Is the dice roller random?
Each die uses an independent, unbiased cryptographic random number from 1 to its number of sides. An earlier result does not determine the next roll, so the same face can appear again.
Can I roll a d20?
Yes. Choose 20 in Sides to roll a twenty-sided die, with a result from 1 to 20. You can roll 1 to 12 of these dice at once, and each result appears inside the die’s outline.
Does it add up the dice?
Yes, the tool shows the total of all dice after each roll. The individual results remain visible, so you can use the dice for an addition prompt as well as read the sum.
Can I flip a coin instead?
Yes. Choose Coin, set the count, and select Flip. Coin mode flips 1 to 12 coins and counts heads and tails.
Can I use the dice roller full screen?
Select Full screen or press F to show only the tool for your projector. Press Esc to exit. On iPhone Safari, where full screen for part of a page is not allowed, the tool fills the browser window instead.
Can I see previous dice rolls?
The last 20 rolls stay in History. You can also turn on Count each face to see how many times each face has appeared. The face counter tracks individual faces, rather than the sums in the probability table.