Multiply the numerator of the fraction (5/6) by 4, how much should be added to the denominator to keep the size of the fraction unchanged.
分数(5/6)的分子乘4，要使分数的大小不变，分母应加上多少．
<gadget id="calculator">4 * 6</gadget>
<output>24</output>

<gadget id="calculator">24 - 6</gadget>
<output>18</output>

<result>18</result>