players participate in a table tennis match, if every 2 players have to play a game, how many games should be arranged in total.
4名队员参加乒乓球比赛，如果每2名队员之间都要进行一场比赛，一共要安排多少场比赛．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<result>6</result>