How can I work out ?-bit version I am running?

I am trying to install Office 2013 and it won’t allow me as I a 32-bit Office program running. Am trying to work out if it is LibreOffice I need to delete?

A running instance of LibreOffice would not (should not) prevent the installation of Office 2013 (although I am sure that Office 2013 suggests quitting all other programs before installing, and for a program like Office that’s probably advice worth listening too).

To determine what version of LibreOffice you have, start one of the Applications … say, Writer … and on the Menu, click ‘help’ / ‘about libreoffice’