Okey, I'm a little stubborn with these kinds of questions in that i HAVE to understand them from every way...Bit silly really since i have the answer buts its reeeeally bugging me i can't get it another way.

4 Dice, what's the probability that at least two or more are the same number?

Well i've done it by considering the fact its 1 - P(they are all different numbers) leaving the probability that at least one must be the same. I started working it out a different way, which didn't work, so settled for the above.

Anywho, on my google travels, i came across this little table:

------------------------------------------Instances -- Probability

All four match ---------------------------- 6 ----------0.46%

two pairs of different numbers ---------90 --------- 6.94%

three dice match-------------------------120 -------- 9.26%

no matches------------------------------360 ---------27.78%

one pair matches ----------------------720------55.56%

TOTAL ---------------------------------1,296--------100.00%

Now, this 'one pair patches' is bugging me.How the hell do you get 720?

Because i was thinking:

4 dice.

Now if we choose any 2 of these dice (4 choose 2 = 6)

As there are 6 different ways to get pairs in two dice {(1,1), (2, 2)...etc}

There must be 6(number of ways to get 2 dice) x 6 instances.

What is it in my thinking that is incorrect?

Thankyou