The page number of a book is 1 to 82 pages, that is 82 pages in total. When adding up the page numbers of the pages of this book, one page number was omitted. The resulting sum is 3396. What is the page number that was omitted?
一本书的页码为1至82页，即共82页．把这本书的各页的页码累加起来时，有一页码漏加了．结果得到的和数为3396．问这个被漏加的页码是几？
<gadget id="calculator">1 + 82</gadget>
<output>83</output>

<gadget id="calculator">82 / 2</gadget>
<output>41</output>

<gadget id="calculator">83 * 41</gadget>
<output>3_403</output>

<gadget id="calculator">3_403 - 3_396</gadget>
<output>7</output>

<result>7</result>