There are a total of 10 athletes in a sports competition. If every two players shake hands once, how many handshakes should they have in total?
在一场体育比赛中一共有10名运动员，如果每两个人握一次手，一共要握多少次手．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">10 * (9/2)</gadget>
<output>45</output>

<result>45</result>