1) For installing OpenOffice you have to first uninstall the LibreOffice which is by default installed in your Ubuntu.

So open the Terminal Window and type the following command and give password.This will remove the LibreOffice completely.

sudo apt-get remove --purge libreoffice-core

(OR)

Open the Ubuntu Software Center and search for “LibreOffice core” and click on remove (uninstall).This will uninstall the LibreOffice completely.

2) Download OpenOffice from its official website.The download file will be in *.tar.gz format.

3) After the file is downloaded, go to the downloaded directory and click on “Extract here”.

4) Now open the Terminal and change the directory to the location where your Extracted Open Office file is present.Just type “cd” followed by drag and dropping the “DEBS” folder or manually do it.

5) Type the following command which will install OpenOffice by installing all the *.deb package files.

sudo dpkg -i *.deb

6) Enjoy using OpenOffice. The default installation location is /opt/openoffice4 and Apache OpenOffice executable is called soffice and is located in /opt/OpenOffice4/program/