A total of 6 teams participate in a basketball league, and a single round-robin match is adopted to determine the outcome (one match between each two teams), how many games will be played in total.
一次篮球联赛共有6个球队参赛，采取单循环赛决定胜负(毎两支球队之间进行一场比赛)，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>