@Jayneck That's just the math part for probability calculations. The problem is too many people assume that such calculations will be accurate predictors in the short run, but they aren't.

For any given roll, the odds of a specific number coming up would be as you posted - and the dice have no memory, so they don't know what they rolled previously.

For the calculations to be even close to accurate predictors you need a large sample size - several hundred, or even a thousand rolls. For a normal game of Catan (usually less than 100 rolls) probability calculations are pretty much useless.

Another thing people forget is that a low probability isn't the same as not possible. The chance of hitting all six numbers in the lottery are one in a few million, but it still happens.