how to display the versioning number of a office365 word document in the word document?

You need to set Sharepoint up to generate a Label field, which it will then update with its version number on each check in.

You can then insert a DOCUMENTPROPERTY "Label" field in the Word document to display the content of the Label field.

The instructions are here:

http://www.bryansgeekspeak.com/2009/03/moss-2007-show-sharepoint-version.html

Word for Mac is a cut-down version that does not have the QuickParts controls shown in that article.

1. However, it DOES have an "Insert Field" control on the Insert tab of the ribbon.
2. Within the Insert Field dialog, you will find a field named DOCUMENTPROPERTY.
3. If you click Options on the DOCUMENTPROPERTY field, it should enable you to select the "Label" document property.
4. If you have set up Sharepoint correctly, that will contain SharePoint's Version number.

Notes:

• Word's Version field has nothing to do with the Sharepoint Version column.  The two are unrelated: Word's Version field does not contain the Sharepoint version number.
• The document must have been added to the Sharepoint library, checked in, and checked out again before the Label field will appear in the document.
• The document must be in .docx format and remain in .docx format.  If you convert the document to any other format, the Label field will be removed.

The thing that usually catches people out is that the document must have already been checked in to Sharepoint, or the field you are looking for will not exist in the Word document.

There are also reports that a heavily-customised version of Sharepoint may not support this method.

Hope this helps

The sharepoint i'm using (which is the office365 online) doesn't seem to have the 'Information Management Policy Setting', which leads to the 'Edit Policy: Document' page. 

Does this mean our sharepoint is a heavily customised version? 

or are they under a different title/settings page? 

Thanks