It took Qiangqiang 18 seconds to walk from the first floor to the third floor. How many seconds does it take him to walk from the first floor to the seventh floor?
强强从一楼走到三楼用了18秒，他从一楼走到七楼需多少秒？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<result>54</result>