When your file doesn’t start on page 1, it is helpful to have the PDF show you the absolute page numbering, not the relative page number in that file. It’s particularly helpful for indexing and other page-number-sensitive markup that editors do.
Here’s how to do it. (A video showing X and XI follows these Acrobat 9 instructions.)
You need the full Acrobat program to customize the page numbering on a PDF. In Acrobat Pro 9, the setting is under Advanced > Document Processing > Number Pages
In the X and XI versions, it works as in this video tutorial.
In the Windows version of Acrobat, look under View > Page Navigation > Page menu item. On Windows, this shortcut is “Ctrl + Shift + N”; on Mac OS, it is “Cmd + Shift + N”. According to http://www.w3.org/TR/WCAG20-TECHS/PDF17