Help with d6

I'd like a formula to determine the following:

What are the chances of two or more of the same number occurring on 2d6, 3d6, 4d6, etc?

I'd be fine with this formula longhand, or for Excel

Quote: ElricGreywolf

I'd like a formula to determine the following:

What are the chances of two or more of the same number occurring on 2d6, 3d6, 4d6, etc?

Easiest way is 1 - the probability of all the dice being different.

For 3 dice it's 1 - (6/6 * 5/6 * 4/6).
For 4 dice it's 1 - (6/6 * 5/6 * 4/6 * 3/6).

HAH! Thank you, I've been trying all kinds of esoteric mathematical wizardry, half-remembered from high school, that involve powers and multiple variables. This is definitely easier!
Cheers!

Quote: ElricGreywolf

What are the chances of two or more of the same number occurring on 2d6, 3d6, 4d6, etc?

Why the nice question?
you must be playing a game I would think

I figured you would want more information like maybe
What are the chances of 3 or more of the same number occurring on 3d6, 4d6, 5d6, etc?

or maybe just

What are the chances of exactly two of the same number occurring on 2d6, 3d6, 4d6, etc?

example
4 six-sided dice
ABCD (1,1,1,1)
AABC (2,1,1) <<< yes
AABB (2,2) <<< yes, yes
AAAB (3,1)
AAAA (4)

I love dice games
Sally