Find the latest build number of office.

Office 2013 and 2016 installs from o365 will update and patch themselves. But I always like to make sure its working and is up to date. This site list how to force and update and check your current version. It also list the latest version number of 2013 which at this time is

• 15.0.4745.1002

Update Office 2013 or Office 365 Most Office 2013 or Office 365 products are kept up to date automatically thanks to a technology called Click-to-Run. If you’d like to verify you’re up to date, check your Office version number and manually update Office if necessary. Check your version of Office Open any Office application, like Word or Excel. Click File > Account. Under Product Information, note the version number below Office Updates. Compare it against the Current Version listed in this article.

Source: Update Office 2013 or Office 365