Add 6 to the numerator of (7/3), how much should the denominator be multiplied to keep the fraction value unchanged.
把(7/3)的分子加上6，要使分数值不变，分母应该乘多少．
<gadget id="calculator">7 + 6</gadget>
<output>13</output>

<gadget id="calculator">13 / 7</gadget>
<output>13/7 = around 1.857143</output>

<result>13/7 = around 1.857143</result>