In a game, there are a total of 10 players. If every two people shook hands once, how many times did they shake hands in total?
在一场比赛中，一共有10名运动员．如果每俩人握一次手，共握了几次？
<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>