There are 10 students playing table tennis, if there is a game between every 2 students, how many games will there be in total?
有10名同学进行乒乓球比赛，如果每2名之间都进行一场比赛，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>