iota-calc...
Key Features: Supports a rich expression format, which is in most cases identical to what you would type in your programming language.
Support for adding unlimited numbers of variables or variable expressions. Built-in debugger that lets you see the expression simplified step by step. Debugger Back-step lets you backup as many steps as you like so that you can replay critical operations. C/C++ operator precedence. Mouse optional, all calculator commands and functions can be done using the keyboard alone. Mini-Calc Mode lets your calculator take up very little screen real estate, and yet remain entirely usable. Running paper tape(s) (1 per calculator) for calculations, allows annotations, and is stored between runs. Built-in Ascii chart makes it easy to look up even invisible characters. View results in big endian (default) or little endian. Numerous built-in unit conversions (memory sizes, lengths, areas, volumes, temperatures, currency etc.) Built-in great circle route and straight line distance calculator. Input/Output Formats: Binary, Octal, Decimal, hexadecimal, Booleans, Characters, UTF-8 (out only), and UTF-16 (out only). Convert automatically between these types in your expression with the keyboard, a button, or a contextual menu. Operators and Functions: Standard: Addition, Subtraction, Multiplication, Division, Modulus, Power, Square Root. Grouping: Parenthesis. Variables: Previous Answer. Bitwise: complement, and, or, xor, shift left, shift right. Comparators: equals, less than, greater than, less than or equal, greater than or equal. Logical: and, or, and not. Trigonometric: Sine, Cosine, Tangent, Arc-Sine, Arc-Cosine, Arc-Tangent, Degrees To Radians, Radians to Degrees. Other: Min, Max, Round, Ceiling, Floor, Absolute Value, Sign. Constants: Pi