I found an odds calculator on-line that is rather useful in determining the odds of success in a battle between two territories. I've tried to tweak it to determine the odds of an elimination run given the total armies your target has and how many countries they're spread over.
So, here's where I'm headed:
On one side, the total number of countries to be taken needs to be factored against your starting number as you will spend one army per country as you proceed. So the first variation on this formula, I simply subtracted one less the total number of countries from the amount you are attacking with. I took one less because the calculator already takes into account the fact that you need to have one extra troop at the end of the battle to win it.
However, the other side of this is that the more countries the target is spread out over, the more times you will be rolling against 1 dice, so the above tweak underestimates the odds of success because it takes the bad part of having to conquer many countries without the good part (many attacks in which you have very favorable odds of not losing any armies).
Has anyone come up with something that can estimate this?