In current Word for Windows, the command is named Page Number, not Page Numbering, and it is on the Insert tab.
To insert page numbers in a header without losing the header text:
- On the ribbon, select Insert.
- Click Page Number and choose the location and style (for example, Top of Page → a layout you like). This inserts a page number field in the header.
- If the header text disappeared, press Ctrl+Z once to undo, then:
- Double-click in the header area to open it.
- Place the cursor where the page number should go (for example, after your existing header text).
- Select Insert → Page Number again and pick the style. Word will insert the page number at the cursor instead of replacing the whole header.
- When finished, select Close Header and Footer or press Esc.
If the first page should not show a page number, in the header/footer tools select Different First Page.
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