I was wondering if my theory on how dragons stack is correct. If one dragon hits a target it wipes out 10% of the enemy units on the target.

So if 2 nukes hit a target at once it would make most sense if it didn't do double the damage, rather it exponentially done less damage ie 2 nukes takes out 19% of units {y=100*(1-(0.9^x))} where y is the percentage taken out and x is the number of dragons, * = multiply, ^=to the power of.

is this correct? (1 dragon = 10%, 2 = 19%, 3 = 27% etc.)

(here is a graph

http://i.imgur.com/2TuPuC6.png)