ChrisJG
Noob
Depends on what math you're talking about. In your example there is an outcome of success or failure. there is a 99.9 repeating % chance of a success. The chance of failure is 0 because the chance of getting .00....1 is actually 0.The problem is that to GET to .9 repeating you must continuously add .xxxxxxxxxx1 to it every time to continue to get to the next 9. There is always that infinite amount that needs to be added to get to the next 9.
That means that an infinite amount of times, .99999 is NOT equal to one.
Lets say in another scenario there is a 100 % chance of success. Therefor there is a 0 chance of failure as well. This is another reason people can argue .9 repeating = 1
EDIT: just playing devils advocate by the way, I also believe the two numbers are unequal