A clock rings once every hour. At 3 o'clock, it takes 4 seconds from the first ring to the last time. At 10 o'clock, how many seconds does it take from the first ring to the last time.
一面钟它每到整点时间响一次，3点钟时它从第一次响到最后一次共用了4秒，10点钟时，它从第一次响到最后一次共用多少秒．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

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

<result>18</result>