For those that do not want to pay Microsoft you can get the open source Libre Ofice or Openoffice and they will open MS documents and output them to MS if done in their native file. Both are free and quite robust. I like the Libre Office but I used to work for Oracle and when they bought Sun Microsystems the application was called Star Office which became Openoffice. Oracle is so tight and will not give away anything they donated Openoffice to Apache so they did not have to support a free product.
LibreOffice and OpenOffice use the same source code and will open their native files in both applications.
So if you do not have MS Office you can still open and export in the MS formats.