Here is an example of the experiment we did:
It looks like it only takes 4 rolls to have a 50% chance of getting a double … smaller than you might think! The more trials we do, the more accurate our results. You can run many trials in the applet below:
You can also use the applet above to try different number of sides on the dice. How many rolls do you think it would take to have a 50% chance to get a double on a 20 sided dice?
If you extend this question to 365 sides … it is the Birthday Problem! How many people do you have to have in a room for there to be over 50% chance of two people sharing a birthday? Try and discover the answer using the applet above, or see our card deck website for the maths behind the answer.