people participate in a table tennis match, and every 2 people play one game, how many games will be played in total?
5个人参加乒乓球比赛，每2个人要打一场，一共要打多少场．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">4 * (5/2)</gadget>
<output>10</output>

<result>10</result>