The school holds a table tennis competition. There are 5 classes in the third grade. Every two classes will hold a game. How many games will the third grade have in total?
学校举行兵乓球比赛，三年级有5个班，每两个班要举行一场比赛，三年级一共要赛多少场．
<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>