There are 10 children attending a banquet. If they shook hands with each other, how many times did they shake hands in total?
有10个小朋友参加宴会，如果互相握手的话，他们一共握了多少次手．
<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>