The big clock on the square strikes 6 times at 6 o'clock, and it takes 10 seconds to finish the knocking; it knocks 9 times at 9 o'clock, and it takes how many seconds to finish the knocking.
广场上的大钟6时敲6下，10秒钟敲完；9时敲9下，多少秒钟敲完．
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>