OpalCalc is a brand new type of calculator for the PC. As easy to use as Notepad or a word processor, OpalCalc allows natural language in the sum and multi-line support so you can go back and adjust your previous calculations on the fly.
For years, PC calculators have been trying to copy handheld calculators in both functionality and appearance. OpalCalc sets out to disregard previous conceptions, and instead we considered how a calculator should behave with a full keyboard in mind. The result is simplicity itself, but with almost spreadsheet-like capability.
OpalCalc features include percentages, currency conversion, custom functions/variables, excellent documentation, colour coding, lightweight size, configurable GUI, hundreds of measures and functions, and lots more. The full version can be obtained with a donation of any amount (even a few pence). There is no time limit in the 'lite version', just a 5 line limit which is very useful for most purposes.