Info-Mac

Download: http://archive.info-mac.org/sci/calc/rp ... or-192.hqx

RPN Calculator is a robust implementation of RPN for Macintosh. It has a
few features that distinguish it from the crowd, such as dealing with
complex numbers the right way and being able to tell you if a number is
perfect or not, among other uncommon functions. This build is functionally
identical to V1.91 and removes the remaining GUI debris from the OS X to OS
9 port.

RPN Calculator is a robust alternative to the Mac OS's built-in calculator
program. It can easily deal with complex number math. RPNC also has other
features that are not common. Version 1.74a is the last PPC build of RPNC,
and as such does not require CarbonLib, making it useable on all Macintoshes
back to those running Mac OS 8.1.