There is a wall clock, and it is struck a few times at any time. If the clock strikes 5 times, it will be completed in 4 seconds. If the clock strikes 10 times, it will be completed in how many seconds.
有一个挂钟，几时就敲几下，钟敲5下，4秒完成，钟敲10下，多少秒完成．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 / 4</gadget>
<output>1</output>

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

<gadget id="calculator">1 * 9</gadget>
<output>9</output>

<result>9</result>