A book, numbered pages, uses 7825 numbers, how many pages does this book have.
一部书，编上页码，公用了7825个数字，这部书共有多少页．
<gadget id="calculator">90 * 2</gadget>
<output>180</output>

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

<gadget id="calculator">7_825 - 9 - 180 - 2_700</gadget>
<output>4_936</output>

<gadget id="calculator">4_936 / 4</gadget>
<output>1_234</output>

<gadget id="calculator">1_234 - 1</gadget>
<output>1_233</output>

<gadget id="calculator">1_000 + 1_233</gadget>
<output>2_233</output>

<result>2_233</result>