Eight students came together, they shook hands once in two, and asked how many times they shook hands in total.
有8个同学走到一起，他们两两握手一次，问一共握手多少次．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">8 * (7/2)</gadget>
<output>28</output>

<result>28</result>