2 must-have business apps

Getting paid and having instant access to documents are necessities for small business owners.

So it's no surprise that two of Google Play's hottest free business apps can transform your Android phone into a mobile cash register ... or a mobile office. (iPhone and iPad versions are also available.)

Meet the dynamic duo:

Square Register. Accept credit card payments in a jif on your Android phone. How it works: 1. Attach the small reader (roughly the size of a Scrabble tile) to your smartphone. 2. Start swiping. The app and the reader are free, but you pay 2.75 percent or $275 a month for the service.

Documents to Go 3.0. View your Microsoft Word, Excel and PowerPoint files with this handy app from DataViz. Upgrading to the full version, which includes editing capabilities, is currently $14.99 (a 50 percent discount).