There are 8 athletes, A, B, C, D, E, F, G, and H. If every two athletes shake hands once, how many handshakes are there in total?
有8名运动员，A、B、C、D、E、F、G和H，如果每两名运动员之间握一次手，共握多少次手．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<result>28</result>