The school holds a table tennis competition. There are 5 students signing up. If every two students play a game, how many games will be played in total?
学校进行乒乓球比赛，有5个同学报名，若每两名同学进行一场比赛，一共要进行多少场比赛．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>