There are 4 teams participating in a football match. If every two teams play a game, how many games will they play in total?
一次足球比赛，一共有4个球队参加．如果每两个球队要踢一场球，一共要踢多少场．
<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>