1. At the end of the previous page (or the end of the second page if the page number is marked at the beginning of the third page), select the menu "Insert/Delimiter/section break Type Next Page".

2. Jump to the page where you want to start inserting page numbers and select View/Header and Footer. The Header/Footer toolbar will appear. You will find that there are a few words "Header-Section 2" and "Footer-Section 2" in the header/footer of this page, and there are the words "Same as the previous section" and the Header/Footer toolbar on the right. Pages before inserting section break Next Page are displayed as Header-Section 1 and Footer-Section 1.

3. This is the key. WORD's definitions of section 1 and section 2 actually allow these two parts to define different headers and page angles. Just let the words "the same as the previous section" disappear in the second section. The way to make it disappear is to click the "Link to Previous" button in the header and corner of the second section, so that the header and corner of the second section can be set with the first one. At this point, set the header/page angle of the second section separately, and select "Insert AutoText/Page Number" on the toolbar.

By analogy, you can arbitrarily insert multiple different consecutive page numbers in a document, select Format Page Numbers, or specify that the page numbers start with any number.