# Rolling a dice many times.

1. Apr 18, 2012

### calvinjhfeng

I know how to calculate the probability of getting a 1 and then 2 or 1 and 1 and etc, that's just 1/6 * 1/6

Now what if I ask, what is the chance of getting a 6 from 3 rolls? Let's say I roll the dice 3 times and all I want is just a 6 from any one of these roll? I just want one 6 from any roll, I don't care if it comes in the first or second or third roll.

I might hear an answer 1/6 , but what if I decided to roll this dice infinitely many times and from that, the probability of getting a 6 is definitely 100%, considering it's a fair dice.

So does rolling a dice extra time will add to the probability of getting a desired number?

2. Apr 18, 2012

### mathman

The easiest way to do this kind of calculation is to consider the opposite event (never getting a 6). Since the probability is 5/6 on any one roll. On 3 consecutive rolls it is (5/6)3, so getting at least one 6 is 1 - (5/6)3.

3. Apr 18, 2012

### calvinjhfeng

o that is simple and quick.
Thank you very much.