The big clock on the square strikes 3 times at 3 o'clock, and it takes 6 seconds to finish. How long does it take to knock 12 times at 12 o'clock?
广场上的大钟3时敲3下，6秒种敲完．12时敲12下，需要多长时间？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">3 * 11</gadget>
<output>33</output>

<result>33</result>