I may be wrong here as I am not a PHP guru.
I am using WP-PageNavi by Lester 'GaMerZ' Chan.
The plug-in works very well but it has one principle issue it refers to the latest page as page 1 and the oldest page have the highest number.
On the surface this works fine but has one very serious drawback. When the pages are indexed by search engines the post URLs per page are constantly changed with each new post, thus making search engine results void. Not a good experience.
I mentioned this to Lester and he is of the opinion this is the order how WordPress returns pages.