When reading a book, you have already read (1/4) of the whole book, and what you have read is how much you have not read
看一本书，已看了全书的(1/4)，已看的是未看的多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(1/4) / (3/4)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>