• Creating:
    • Google Docs: File > Download As > choose the pertinent Microsoft Office format
    • LibreOffice: File > Save As > file format >  choose the pertinent Microsoft Office format
    • iWork (Pages, Keynote, Numbers): File > Export will give you the options your need.
  • Opening / Editing:
    • Google Docs > choose Upload and check the box to convert to native Google Docs format
    • iWork and LibreOffice > File > Open