How to start numbering 1 in the middle of the document:
In the non-header and footer format, select page layout --- separator -- next page in the blank space of the previous page that needs to be marked with serial number 1, and then delete the page break on the next page. Backspace cannot delete the page break. You need to use the Delete key to delete; then on the page marked with serial number 1, select serial number 1. In the header and footer tools, you can see that the link to the previous header option is selected, and click it again to indicate that it is not selected; finally Just delete the pages that do not require page numbers, and subsequent page numbers will not be affected.