With the evolution of smartphones and their processing power, you are now able to do all the tasks at the touch of your finger that you traditionally performed on a laptop or a desktop.
I had couple of apps on my Android through which I can only view documents but was never able to edit. But now that has become history, today I have installed couple of free document editing apps (Kingsoft Office, Olive Office Premium) and was able to do things that I dreamt of in the past.
Kingsoft Office:
Provides edit features for Word, Power point and Spreadsheet and supports multiple file types of MS Office (.doc, .docx, .xls, .xlsx,.csv, .ppt, .pptx). It is an ultimate tool for professional and for personal use. You can save documents into PDF formats or convert an existing document into a PDF file. The interface is user friendly and supports other languages too. You can save files on the cloud.