Nirav
Nirav reviewedNumiA beautiful calculator app for Mac
 RecommendedPros: 

Incredibly useful and powerful

Cons: 

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.