If you are using “Table of Contents” in Google Docs for creating text documents. Especially containing lengthy content with bunch of sub-titles, then you should have annoyed due to the limitations of some features under “table of contents” in Google Docs. Table of contents has the ability to accumulate all your titles and sub-titles of your document at the top, so that you can make a index like structure of the document. You should be familiar with this if you have used MS Word at large.
Some of the feature Google Docs missing over MicroSoft Word are Auto numbering the titles in ‘content’ part and also in ‘Table of Contents’ part and including page numbers for titles in ‘Table of Contents’.
You can insert ‘Table of Contents’ in any Google Document from ‘Insert’ menu. You have to select appropriate Title format from secondary menu ribbon. For example, Heading 1 for Title, Heading 2 for Sub-title and so-on. Refer following picture to understand better.
For more understanding here is the support page for table of contents for Goolgle Docs
So, here is the solution for Auto Numbering ‘Table of Contents’.
To auto-number your table of contents (like you seen in title picture of this post), all you have to do is install this table of contents chrome extension. After installing, a side bar will appear on right side of your doc editing page as illustrated in the picture below. From where you can access ‘Table of contents’ across your document when you scroll and it also provides few options to choose numbering styles and a option to refresh the contents. This extension adds the number to the titles inside the document, so it in turn updated to ‘Table of contents’ in doc.