10Calc is an adding machine style 10-key calculator for financial and business use cases, particularly accounting. It supports all the functions of business desktop calculators, such as averages, margins, and tax calculations. What makes 10Calc special compared to other Android calculators is its scrolling "tape" journal for displaying all operations. The tape can even be shared with others or printed directly to a local printer. Another great benefit is its portability: 10Calc is always there on your phone!
Note: 10-key calculators work differently from ordinary consumer calculators, so unless you are familiar with 10-key calculators, this is probably not for you.