Reading a story book, Congcong read half of the book in the first week, the remaining half in the second week, and 4 pages in the third week, just finished the book, how many pages are there in the story book ．
看一本故事书，聪聪第一周看了这本书的一半，第二周看了余下的一半，第三周看了4页，刚好看完这本书，这本故事书有多少页．
<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>

<gadget id="calculator">4 / (1/4)</gadget>
<output>16</output>

<result>16</result>