I guess we could have an like some sort excel spreadsheet that works it out by the amount of units and a random factor. I would make one but the random funtion doesnt work on mine becasue I dont have something installed :/ .
EDIT: here we go, the random numbers change everytime you change something. If it doesnt work then goto tools/Add-ins and enable Analyasis tool-pack (dont ask me why, the little cat (I dont like the paperclip) told me to do it.)
EDIT 2: Oh yeah, the person with the highest nubmer wins. I would put a fancy IF command that said things like "easy victory" or "close victory" but I cant remember how and I can be bothered to find out.
EDIT 3: Oh yeah (again) the units have to be a value of 1-10 for it to work.