In a table tennis match, there are 4 players A, B, C, and D. If there is a match between every two players, how many games will there be in total?
在一次乒乓球比赛中，有甲、乙、丙、丁4名选手，如果每2名运动员之间都要比赛一场，一共要比赛多少场．
<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>