In a football match, there are 6 teams in a single round robin match, how many matches are needed in total?
足球比赛中，有6支球队进行单循环赛，共需要赛多少场？
<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>