When printing the page number of a certain book, the number of numbers used is 975 (for example, 2 numbers are used on page 23, and 3 numbers are used on page 100), so how many pages should this book have?
印刷某一本书的页码时，所用数码的个数是975个(如第23页用2个数码，第100页用3个数码)，那么这本书应有的页数是多少．
<gadget id="calculator">100 - 1</gadget>
<output>99</output>

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

<gadget id="calculator">975 - 9 - 180</gadget>
<output>786</output>

<gadget id="calculator">786 / 3</gadget>
<output>262</output>

<gadget id="calculator">99 + 262</gadget>
<output>361</output>

<result>361</result>