LibreOffice – A free complete office suite

A free portable complete office suite

LibreOffice Portable is a full-featured office suite — including a word processor, spreadsheet, presentation tool, drawing package and database

It includes all the tools to replace Microsoft Office or other office suites.

Writer – word processing

Calc – spreadsheet

Impress – multimedia presentations

Draw – graphics and diagrams

Base – Database front end

Math – formula editor

It also supports additional features through extensions

PDF Import

Presentation Minimizer  – Reduces the file size of the current presentation

ReportBuilder: To build good-looking database reports

Wiki Publisher : the Wiki Publisher extension lets you create Wiki articles on MediaWiki servers

Read more here

You can get a portable version of LibreOffice from here