There are 4 teams in each group of the World Cup football match. Every two teams in the group have to play a game, how many games need to be played in each group.
世界杯足球比赛的每个小组有4支球队．小组内每两去球队之间要踢一场比赛，每个小组内需要踢多少场比赛．
<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>