8 students participate in a table tennis match. Every two students need to shake hands once. How many handshakes should they have in total?
8个同学参加乒乓球比赛，每两人要握一次手，一共要握多少次手．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<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>