RedCrab is a scientific, statistics and finacial calculation software with a full screen formula editor. The mathematical expressions can be entered in an editor window similar to a piece of paper. The editor supports the entry of complex algebraic equations like fractions, square roots, exponents, variables etc. for technical and scientific applications.
No one today would want to work with word processing program that simulates a typewriter, for example, no copy, paste and edit. For typo errors, whole text must be rewritten. But most PC calculators are just unflexible simulations of pocket calculators.