Over many years of my engineering career I owned the HP 35, 45, 55, 65, and 15. This app operates just as the physical HP15C. It's a joy to get an app that uses RPN. It works.

For OS 10.7.5, and OS 10.12, this is a as good as my HP 35 personal calculator, both of which do more than I ever needed. RPN is easy to work with.

The calculator worked well for years on both my iphone and macbook. The iphone version stopped working. Despite numerous attempts for assistance, I have not been able to get any help. The macbook OSX version continues to function as expected.

Oddly, this calculator lacks standard red/yellow/green window management buttons… and the ability to minimize by clicking it’s (non existent) menu bar. Didn’t think much of it at first, but is becoming more & more annoying with every use. Also, numbers can be copied to the clipboard by pressing the ‘CP’ key, where the 'on' button is on the physical machine; but numbers can’t be pasted in to the calculator! Wouldn’t have bought had I known before hand. Additionally, it pops up ‘nag’ boxes soliciting ratings & reviews. Who needs/wants that?

Works good, only 3 significant digits in floating point. There may be something I don't understand about it.

I purchased this app to make a simple calculation and it can't do it........ I need a refund ASAP but no way to request one...

I own an HP15C, and I like having this on my other devices to use when I’m away from my desk. No complaints.

I think this is a great homage to the HP hand calculator and I use this often. I’d rate it 5 but it needs an “always on top” selection in preferences.

Those who can use no other calculator than the HP15C need no further encouragement — it’s the same beast.

I have owned a 15C for many, many years and just love it. I now have it on my Mac and iPod touch. Just love it and glad to have it always with me!