10 people play a table tennis match, with each pair playing one game between two people. Q: How many games are there in total?
10个人进行乒乓球比赛，每两个人之间比赛一场．问：一共要比赛多少场？
<gadget id="calculator">10 * 9</gadget>
<output>90</output>

<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<result>45</result>