You are downloading the RPN Calculator XAP file v184.108.40.206 for Windows Phone. RPN Calculator is a free Productivity App: RPN Calculator is a calculator that uses the Reverse Polish Notation method of user interaction, which is typically popular with people who deal with. You can now download the offline XAP package file to install & try it.
Download Locations for RPN Calculator 220.127.116.11 XAP file
To try to install it manually from an SD card, you should choose one of the server location above to get the offline RPN Calculator XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.