OpalCalc is a powerful calculator that allows you to insert natural language as part of the sum, along with multi-line support so you can go back and adjust your previous calculations. It features a lightweight footprint, on-the-fly calculation as you type, percentages, variable support, hundreds of units and functions, extensive notation support, intuitive design/documentation.
v1.6 [Jan 30, 2013]
The portable versions of OpalCalc wouldn't extract properly under certain programs. This should be fixed now.
In version approx 1.30 and earlier, functions could use constants such as pi and global variables (providing they don't clash with the parameter variables). This functionality has now been restored for good.
Programmers Calculator that supports full precedence, large range of operations
