4.2) I play a game with an unrated player. How does it affect my BKR?

Each player has a BKR although it is not displayed. Players start with BKR = 1300 and the BKR is not shown until he/she finishes at least 4 rated games. Furthermore, BrainKing displays estimated values of your particular BKR change below the selected game board, depending on the game result (win, draw or loss).