Apache OpenOffice (AOO) is an open source office suite that is available across all platforms. With over 20 years of development behind it, the suite is a consistent all-round performer.
Like LibreOffice, OpenOffice uses the Open Document format (ODF). It can view and edit a large number of other file types, particularly MS Office files. OpenOffice cannot save or edit documents using the open XML format e.g. DOCX. You can however open these files and save them as a different format.
As it is an open source suite anyone who has the know-how can suggest improvements or fix any bugs. As with other open source applications it has a great online community who are always willing to lend a hand to other users.
While the formula tool, Math, has the basic features needed to calculate equations, it is not for advanced users. OpenOffice has the option to create basic presentations through Impress, but there are very few design templates compared to PowerPoint.