Rating system for online games in Heroes of Might and Magic IV.

I remember that in such a case, the player who takes first place would have a Rating of around 3000. What is this needed for? It's to check what that tricky sign – raising to a power or taking the cube root – actually means, and how the number 6000 will behave. We need to take an abstract tournament, say with fifteen players. Assign them places and, assuming that the Old Rating of each is ZERO, calculate each player's rating for the tournament. What will the result be? Optimal, you can practice ;)