In the table tennis trials, each player has to play one game against other opponents. If 10 people sign up, how many rounds will there be in the trials?
乒乓球选拔赛，每个选手都要和其他对手比赛一场，若有10个人报名，选拔赛一共有多少场．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">10 * (9/2)</gadget>
<output>45</output>

<result>45</result>