[Pre-BB] MapleStory Formula Compilation

is there any monster drop formula? like how to calcualate the chances of an item being dropped?

Monster drop chances are server side data, so we cannot extract that. There was a big extraction of said data in another version where it was leaked, but that disappeared off this forum quickly. Some people may still have it, but it doesn't have all the monsters. Mostly just the main stuff (Ludi, Orbis, Nath, Leafre monsters).