This RPN calculator always stays on top, whether it's the active application or not. It's very handy when you need to go back and forth between the calculator and another window, but don't want the calculator to get lost.
Always on Top RPN Calculator v2.2 MacOSX Retail-CORE
The RPN behavior in this app is based on classic HP calculators. All the essential functions for everyday calculation are included. All memory registers are saved when you quit the app.
What's New in Version 2.2
Added article about RPN calculators.