I still have the RPN listing I wrote years ago for Free42, but when I re-key it into both my physical HP-42S and the Free42 app on my iPhone it simply refuses to give the expected results—no error messages, just wrong answers. I need a fresh pair of eyes to step through the code, spot whatever subtle logic or state issues have crept in, and hand back a version that runs flawlessly on both the original calculator and the modern emulator. You’ll receive my exact program text plus a short note describing the correct outputs I used to get. Please trace the execution, locate the trouble spots, and supply: • A corrected, fully tested program listing ready for direct key-entry or .raw import into Free42 / HP-42S • A brief explanation of what was wrong and why your fix works • (Optional but appreciated) any tips for transferring or storing the program safely between devices Acceptance is simple: load your version, run my sample data, and watch it return the expected figures every time. Experience with HP-42S keystroke programming, Free42, and general RPN debugging will make this a quick win. Let me know if you need any extra information—I’m happy to supply whatever helps get this classic routine back in shape.