It takes 3 seconds to strike 4 times at 4 o'clock, so how many seconds does it take to strike 8 times at 8 o'clock?
4时整钟敲4下需要3秒，照这样计算，8时整钟敲8下需要多少秒．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">3 / 3</gadget>
<output>1</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">1 * 7</gadget>
<output>7</output>

<result>7</result>