There are 5 classes in the third grade holding a tug-of-war competition, and there will be a game between every two classes. How many games will there be in total?
三年级5个班举行拔河比赛，每两个班之间要赛一场，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>