RPN-45 HD

I love this app. I bought a HP 45 while in college. If I am not mistaken, it costed more than $350. I am of the generation that learned both slide rule and calculator. I would not be able to graduate without my HP 45. I still have it stored somewhere in a box. I am so used to RPN calculators that I have to think when I use a normal calculator. I recently got an iPad Air 4 and was looking for a calculator app. So happy to find this one. I am amazed that I still remember how to work this. Considering that I have long retired and have not use a scientific calculator for many years. A financial calculator would probably be more useful but then it would not put a BIG smile on my face when I am using this HP 45 app.

I have been using this app for several years. I still have one of the original HP 45 calculators. Has it really been 45 years? This App is my go to calculator. Highly recommended.

This app is a great emulator of the classic HP-45 Scientific Calculator, in look, feel and function. It keeps getting better and better with each update. It offers full complex number functionality, even surpassing that of the HP-15 in complex mode. It comes with many powerful functions, which are actually sophisticated programs, including: 1. Linear Equations -- this lets you solve simulatneous equations for X & Y and in complex mode can solve for the real and imaginary parts for X & Y. 2. Quadratic Equation Solver -- solves entirely within the stack. 3. Cubic Equation Solver -- solves entirely within the stack. 4. The Factorial (n!) also doubles as a gamma function. By subtracting 1 from X and pressing n! you can get the gamma function of any positive or negative number and not just integers. 5. It offers full Linear Regression & Linear Estimate and many other statistical functions. 6. Full calendar, clock and timer functions. An alternate view shows full contents of stack, last-X and all 18 numbered registers, and in complex mode you can see both the real and imaginary parts of all stack & last-x registers. While the original HP-45 had 10 digit accuracy, this app has much greater accuracy as it carries far more digits in its internal calculations. This app is a companion to RPN-45 SD (for iPhone). I have both and highly recommend buying BOTH versions so you get the extra benefits of the iPad version and the portability of the small device version. Truly elegant design. I love the quality of cuveesoft's calculators!