There are 5 students in the art group. After the school starts, every two students have to shake hands at the first activity. How many times do they shake hands in total?
美术小组有5名同学，开学后，进行第一次活动时，每两个同学都要握一次手，他们一共握多少次手．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">4 * (5/2)</gadget>
<output>10</output>

<result>10</result>