There is also a multiplier applied to the rating change based on the number of players. The multiplier is 1 for two player games and \smaller for larger players. The reason is as follows: If you are playing a 3 player game and you beat player A, you probably also beat player B. Thus you should receive not as much rating for beating B as you might in a two player game with B.
The constants actually used are not the best and also appear to differ from game to game (for the same number of players), but the idea is right.
The constants actually used are not the best and also appear to differ from game to game (for the same number of players), but the idea is right.