To remove the page number from those divider pages, hold down Shift + Command/Ctrl and click the page number. It will be "released" from the Master Page and you can delete it. Then you'll have to use Page Numbering and Section Options as mentioned by @SJRiegel to have your page numbering completely skip that page. It's not absolutely necessary, though, in my opinion, if the last page is 8, then the divider page counts as 9 (but doesn't display the number), and the next page of text starts at 10, well that's fine, I don't think it will be confusing and is fairly common practice. Would also save you the trouble of re-numbering.