OpalCalc

Since I am working a lot with number, prices, and misc calculation, I need an easy calculating app that shall at least mimic how easy it was writing calculation on paper.

This app have it. It can also save a group of calculation into files or export it to spreadsheet, which is good to create a template of simple calculation like I used on projects or application development proposals.

Plus, this app have method to stay on top of other app and global shortcut. Mapping the shortcut to UHK make it really easy to use.

It is freemium, the free version gives you 5 lines of calculation. If you are a casual user, free version might be good for you, but for a more serious person, you might want to pay for it, and get a full benefit of this application.

Still the best plain-text calculator for daily use for me. And it can also be used for complex calculation.

This is a gem of a calculator. Super-easy and every conversion you can think of, including the all-important currency conversions with auto-updating rates. Most functions and features are intuitive: just type the calculation pretty much as you would say it out loud and OpalCalc will probably understand what you need to do. But if you get stuck the user guide online is quite detailed and full of examples.

Also: developer is responsive and helpful.

It has 2 panes, the left can contain variables and it is easy to use. You can save sheets of calculations if you wish.

Insanely underestimated calculator, it offers many user friendly options and can convert also units and currencies in a breeze. It's also insanely resizable and fast to open. I recommend it over any other graphical calculator.

1. Really nice calculator because you can easily add custom functions to fit your style and your job. In my case, as a web developper a function to easily calculate width of an element in a webpage.
2. Also the mix between text and numbers is awesome because it is easier to make sense of what you just did. For example for some cash spending. Having the label besides the number really helps.
3. Nifty conversion and calc (goodies) about time and cash rate. Wow, how many times did I check USD to CAD dollars before an online buy.