There are 6 teams participating in a football match, and there is a match between every two teams, so how many games will be played in total?
6个球队参加足球比赛，每两个队之间都要进行一场比赛，那么一共要进行多少场比赛．
<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">6 * (5/2)</gadget>
<output>15</output>

<result>15</result>