Xiao Ming reads a book and reads 105 pages in the first 3 days. Xiao Ming spends 12 days finishing the book. How many pages does this book have?
小明看一本书，前3天看了105页，小明共用12天把这本书看完，这本书有多少页？
<gadget id="calculator">105 / 3</gadget>
<output>35</output>

<gadget id="calculator">35 * 12</gadget>
<output>420</output>

<result>420</result>