It won't get you quite the same power as a proper RPN scientific, but Cabamap is great: http://www.ticalc.org/archives/files/fileinfo/323/32326.html http://www.

It won't get you quite the same power as a proper RPN scientific, but Cabamap is great: http://www.ticalc.org/archives/files/fileinfo/323/32326.html http://www.ticalc.org/archives/files/fileinfo/323/32326.html "Cabamap is a flash application for the 83+/SE that performs arbitrary-precision integer calculations. Simply stated, it can do things like calculate the exact value of 2000! or 2^1024. It uses RPN (Reverse Polish Notation) as the user interface, and is intended as a complete system for long integer calculations. The only limit is available memory (roughly 24000 digits)."