There are 4 football teams, and the round-robin system is adopted, that is, every two teams have to play one game, and finally the rankings are ranked according to the results of each team. How many games are there in total?
有4支足球队，采用循环赛制，也就是每两队都要赛一场，最后根据各队的成绩排出名次．这次比赛一共要赛几场？
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<result>6</result>