Editing word/excel on iPhone?

IIm looking at buying a new phone. I want to use the phone for apps and work mainly, so it is important I can open and edit word/excel/pdf files. Can you do this on Iphone for free?

You will need the Excel app and Word app if you want to edit an excel spreadsheet/Word document on your iPhone

https://itunes.apple.com/...83407?mt=8

https://itunes.apple.com/...47913?mt=8