If a book is printed, the page number of the book uses 2013 numbers, so how many pages does the book have.
印一本书，书的页码一共用了2013个数字，那么这本书一共有多少页．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">1 * 9</gadget>
<output>9</output>

<gadget id="calculator">100 - 10</gadget>
<output>90</output>

<gadget id="calculator">2 * 90</gadget>
<output>180</output>

<gadget id="calculator">9 + 180</gadget>
<output>189</output>

<gadget id="calculator">2_013 - 189</gadget>
<output>1_824</output>

<gadget id="calculator">1_824 / 3</gadget>
<output>608</output>

<gadget id="calculator">608 + 99</gadget>
<output>707</output>

<result>707</result>