[BruceZ]

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Can someone point out the method to compute the probability of rolling a double when you have "n" dice? i.e. If you have 2 dice, the probability is 1/6, if you have three dice, it is...?

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This is 1 minus the probability of all dice being different.

For 3 dice:

1 - 6*5*4/6^3 = 44.4%

For 4 dice:

1 - 6*5*4*3/6^4

For 5 dice:

1 - 6*5*4*3*2/6^5

For 6 dice:

1 - 6*5*4*3*2*1/6^6

In general for n < 7:

1 - P(6,n)/6^n

Where P(6,n) is permutations of 6 things taken n at at time, or 6!/(6-n)!


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and if you have 7 dice, the probability must be 1.

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Correct.