There are 6 football teams in the Olympic Games. They meet each other. How many matches are there in total?
奥运会上有6个队进行足球赛，他们队队见面，比赛场次共多少场
<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>