Free42

My physical HP calculator died after 36 years and like many old engineers (I suspect), I wouldn’t use anything else. I tutor high school kids, with their TI 83’s and 84’s. Even though they can text much faster than me, an RPN calculator runs circles around them. This app is a perfect replica and I urge anyone who is allowed to use an iPhone to try it. It takes about 20 minutes to get used to a completely different way of operating, but you won’t ever go back to algebraic entry.

Works like it should! Great tool & good fun to use. Thank you

I still have my 42S from high school and will only use RPN. This is a fantastic app! Accurately mirrors the functionality of the original. Bravo!

Best calculator app on the App Store. Also great if you want to learn RPN before buying a physical RPN calculator. Based on the open source Free42 emulator, so no ads or bloatware.

Great calculator. I can key in my programs and not lose them when my battery needs to be changed. Thanks !!

If I had only known. I had 2 and gave away one of them to my brother, he did not understand what he had. When mine finally crapped out the other one was long gone. Thank you for this. As good or better then the original.

Use it all the time. RPN is so much better than algebraic once you know how to use it. Unfortunately next generation of school kids aren’t being exposed to its advantages. This app is great. Keep up the good work and pls try to maintain backwards functionality to earlier iOS so it will continue to function on older phones etc.

I used the HP42S throughout high school and university. It was the best but has been lost through the years. This app brings it all back to me now. Thank you so much for developing it! Works just like the real thing!

UI and graphics could be improved, but the functionality is solid.

As a long time rpn user this is a good app. My old HP cratered and this works just like it did and one less device to tire around