There is a tug-of-war competition in Xinhua Primary School. There are three classes in the third grade. Every two classes compete once. How many times are there in the whole grade?
新华小学进行拔河比赛，三年级有3个班，每两个班要比一次，全年级一共要比几次？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">2 * (3/2)</gadget>
<output>3</output>

<result>3</result>