In a sports league of n teams in which each team plays every other team? twice, the total number n of games to be played is given by the equation shown below. nequals=n squaredn2minus? n what is the total number of games to be played in a football league having 21? teams?

We are given the data here that there are 21 teams and that in the tournament, for each opponent, one team has to play with each other twice. The formula to follow here is T = n*(n-1)*z/2 where T is the total number of games played in total in the tournament, n is the number of teams who participated and z is the number of times they have to face in the eliminations. 2 is attributed to prevent the repetition of  the count in the reverse of roles of the opponents. In this case, upon substitution, then T =21*20*2/2 = 420 games in total.