Because you also did it wrong.
500*1.15^12=2700 when rounded up.
Never did I say anything about a 1.12. And where did you even get -50?
EDIT: For that matter, both values I gave were from the full equation and you just did the xpup equation minus a random 50.
Last edited by FrostWyrmWraith; 01-23-2013 at 10:11 PM..