You can easily insert the page number of the next page in a footer by using a field.
The page number is only displayed if the following page exists.
Choose Insert - Header and Footer - Footer and select the page style that you want to add the footer to.
Place the cursor in the footer and choose Insert - Field - More Fields.
In the Fields dialogue box, click the Document tab.
Click 'Page' in the Type list and 'Next page' in the Select list.
Click a numbering scheme in the Format list.
If you select 'Text' in the Format list, only the text that you enter in the Value box is displayed in the field.