It takes 6 seconds for the clock to strike 4 times at four o'clock, and so on, how many seconds does it take to strike 12 times at twelve o'clock.
时钟四点敲4下，用时6秒，依此类推，十二点敲12下，用时多少秒．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

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

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

<gadget id="calculator">2 * 11</gadget>
<output>22</output>

<result>22</result>