Calculator software try too hard to imitate the real thing. They end up big and clunky and their limitations are carried on. Kalq is a user experience experiment to discover an elegant solution to everyday calculations.
Plus42 Alternatives
Plus42 is described as 'Advanced scientific programmable calculator, based on Free42. Free42, in turn, complete re-implementation of the HP-42S scientific programmable RPN calculator, which was made from 1988 until 1995 by Hewlett-Packard' and is a Calculator in the education & reference category. There are more than 25 alternatives to Plus42 for a variety of platforms, including Windows, Android, Mac, Linux and Web-based apps. The best Plus42 alternative is SpeedCrunch, which is both free and Open Source. Other great apps like Plus42 are Qalculate!, fxSolver, Numbat and Numi.