Forget about googling any further. Here are two separate links that fully explaines numbering within Word...2 of the best resources around. Now, I see that you are using the 2013 version while the links that I am providing are for earlier version BUT...they probably are still applicable and the information is excellent. Hope they help you...

http://www.word.mvps.org/FAQs/Number...gExplained.htm

http://shaunakelly.com/word/numberin...numbering.html