Field time: n(n- 1) /2

Reason:

Because a * * * has n teams, each team has to play a game with other teams (n- 1) except itself, so the total number of games of the n teams is n(n- 1), but it includes repeated games like A versus B and B versus A, and the title stipulates that every two teams only play one game, so in the end.

For reference! JSWYC