Numi is a handy calculator app for macOS. It allows to describe tasks the natural way and instantly get an accurate answer. For example, $20 in euro - 5% discount or today + 2 weeks
Incredibly useful and powerfulCons:
Currently saves as .numi file. Export as txt / csv can be really powerful feature to have.
Love every bit. From simple design to the capabilities that it has. I generally travel around and inbuilt currency converter comes in very handy. The latest build is awesome where it lets me save and retrieve the files on need basis.