The Windows calculator is not an impressive application, to say the least. It leaves a lot of room for improvement and user-friendliness. Here to bridge that gap is a wonderful desktop application called OpalCalc.
Opal OpalCalc: Cool Text based Calculation App To Replace Your Windows Calculator
OpalCalc is an excellent calculation app for Windows computers with .NET 3.5 or higher installed. The app lets you type in your calculations as you normally would on a piece of paper – by indicating which value belongs to which item/expense. Your total is then easily calculated using the dedicated word ‘total.’ You can also assign values to variables and use those variables to calculate formulas.