A book has 123 pages. How many times does the number "1" appear in the page number of this book?
一本书有123页，在这本书的页码中，数字"1"出现了多少次．
<gadget id="calculator">10 + 10</gadget>
<output>20</output>

<gadget id="calculator">13 + 20 + 24</gadget>
<output>57</output>

<result>57</result>