Xiao Ming reads a 630-page storybook and has already read (1/7), how many pages are left?
小明看一本630页的故事书，已经看了(1/7)，还剩下多少页没有看？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (1/7)</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">630 * (6/7)</gadget>
<output>540</output>

<result>540</result>