Just to clarify for some of you. Lets say that it has a drop chance of 1% to simplify and you have done 242 attempt so far. The chance of you getting the drop at least once during all those runs would then be
1 - (99/100)^242 ~= 0.91 ~= 91%
But since you did in fact NOT get the mount in the 242 attempts, you are back where you startet. Like someone already pointed out the probabilities doesn't add up.