The NRR in a single game is the average runs per over that team scores, minus the average runs per over that is scored against them. The NRR in a tournament is the average runs per over that a team scores across the whole tournament, minus the average runs per over that is scored against them across the whole tournament. This is the same as the weighted average of the run rates scored in each match (weighted by the lengths of the innings batted compared to the other innings batted), minus the weighted average of the run rates conceded in each match (weighted by the lengths of the innings bowled compared to the other innings bowled). This is "not" usually the same as the total or average of the NRRs from the individual matches in the tournament.