A total of 6909 digits are needed for the pages of a storybook. How many pages does this book have?
一本故事书的页数一共需要6909个数码，这本书有多少页？
<gadget id="calculator">2 * 90</gadget>
<output>180</output>

<gadget id="calculator">3 * 900</gadget>
<output>2_700</output>

<gadget id="calculator">6_909 - 9 - 180 - 2_700</gadget>
<output>4_020</output>

<gadget id="calculator">4_020 / 4</gadget>
<output>1_005</output>

<gadget id="calculator">1_005 - 1</gadget>
<output>1_004</output>

<gadget id="calculator">1_000 + 1_004</gadget>
<output>2_004</output>

<result>2_004</result>