There are a bunch of discs, 3 of which are red, accounting for 3/8 of the whole. If one more red disc is added, how much of the whole is the red disc.
有一堆圆片，其中3片是红色的，占整体的(3/8)，若再增加1片红色的，这时红色的圆片占整体的多少．
<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">3 / (3/8)</gadget>
<output>8</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>