8 students are playing table tennis. It is stipulated that every two students have to play once. How many games are needed in total.
8名同学进行乒乓球比赛，规定每两名同学都要比赛一次，共需要比赛多少次．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">8 * (7/2)</gadget>
<output>28</output>

<result>28</result>