There are 5 students participating in a table tennis match. Every two students will play one game. How many games will be played in total?
一场乒乓球赛，有5名同学参加，每两名同学要进行一场，一共要进行多少场．
<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>