There are 4 football teams participating in the competition, each two teams will play one game, how many games will there be in total?
有4个足球队参加比赛，每两个队都比赛一场，共比赛多少场．
<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>