There are 7 basketball teams in the third grade. Every 2 classes have a basketball game. How many games are there in total?
三年级有7支篮球队，每2个班都要进行一场篮球比赛，一共要多少场比赛．
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">6 * (7/2)</gadget>
<output>21</output>

<result>21</result>