Did you know that WordPress allows you to split a single post or a page into multiple pages? All what you need too do just add <!-nextpage-> tag in your post or page textarea. So, if you have a very long post article and you want to split it then just add Page-Link tag after each paragraph where you want to have a page break.
But remember that you need to use a Text/HTML Tab in your editor if you want to add <!-nextpage-> tag. Also, your WordPress Theme must support the page links feature.
If page pagination is not showing up after you have added <!-nextpage-> tag then open your single.php (Single Post) or page.php (Page) and check if you have this code:
wp_link_pages();
If you do not see it then just add it after the content ( the_content() ).
You can learn more about Page Links here: http://codex.wordpress.org/Styling_Page-Links