One day Mr. Liu went to work. When he passed the clock tower, the big clock of the clock tower struck seven o'clock. He looked at his watch and found that it took 42 seconds from the first to the seventh. Teacher Liu suddenly came to the school. Then he asked his students the following question: It takes 42 seconds for the big clock on the bell tower to strike seven times, how many seconds does it take to strike twelve times? Smart students, how many seconds do you think it takes.
一天刘老师去上班，经过钟楼时，钟楼的大钟恰好敲响七点，他看了看自己的表，发现从第一下到第七下用时42秒，刘老师忽然来了灵感，到学校后对他的学生提出下面的问题：钟楼上的大钟敲七下需42秒，敲十二下需要几秒呢？聪明的同学，你认为需要多少秒．
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">42 / 6</gadget>
<output>7</output>

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

<gadget id="calculator">7 * 11</gadget>
<output>77</output>

<result>77</result>