A page counter adds a professional appearance to your report, and is very easy to add. Normally a page counter is added to the top or bottom of a page; a good place is the Page Header location.
The Report Builder has a built in variable named Page_Counter that keeps track of how many pages have been generated. This variable is accessible from the Dictionary. To add the page counter to a page create a new empty frame inside the desired report band, then select the page counter variable from the Dictionary:
Shown above is a new frame with a Page Counter added to it. The picture button (the one with a flashlight icon) was clicked to show the dictionary. Underneath the "Others" topic 'Built-In Variables' the entry named 'Page Counter' will be double clicked, which inserts the '=Page_Counter' string into the contents entry field.
You can also manually type in the "=Page_Counter" into the entry field; the dictionary simply provides an easier access to that variable that contains the page counter.