Calculate the factorial of the number of teams in the round-robin schedule. Factorial equals the number multiplied by each integer less than that number. Five factorial equals 5 times 4 times 3 times 2 times 1. For example, if you have five teams, calculate five factorial to be 120.
Subtract 2 from the number of teams in the round-robin schedule. In this example, subtract 2 from 5 to get 3.
Calculate the factorial of the Step 2 result and multiply by 2. In this example, calculate 3 factorial to be 6 and multiply 6 by 2 to get 12.
Divide the Step 1 result by the Step 3 result to find the number of games in the round-robin schedule. In this example, divide 120 by 12 to find you would need to play 10 games to have each team play each other once in a five-team pool.