A book has 300 pages. Xiaohong reads (1/2) of the whole book in the morning and the remaining half in the afternoon. What percentage of the whole book does the part she didn’t read account for?
一本书300页，小红上午看了全书的(1/2)，下午又看了剩下的一半，没有看的部分占全书的几分之几？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>