There are 8 students in the mathematics interest group in class 1 of the sixth grade. If every two students have to make a phone call between them, how many times will they have to make phone calls in total?
六年级一班数学兴趣小组一共有8名学生，如果每两人之间都要通一次电话，一共得通多少次电话．
<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">8 * (7/2)</gadget>
<output>28</output>

<result>28</result>