The school wants to hold a basketball game. There are 5 classes in the sixth grade. If every two classes have games, how many games are needed in total?
学校要举行篮球比赛，六年级有5个班，如果每两个班都要比赛，那么共需比赛多少场．
<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>