# RPN-35 SD — user reviews > 14 indexed App Store user reviews of RPN by CuVee Software, rated 4.40/5 from 14 ratings. - Source: https://appshunter.io/ios/app/rpn-35-sd/id956224485/reviews - App overview in markdown: https://appshunter.io/ios/app/rpn-35-sd/id956224485.md - Rating breakdown: 5★ 10 · 4★ 0 · 3★ 3 · 2★ 1 · 1★ 0 ## Most critical reviews (10 lowest-rated) ### 2/5 — Good however… *2025-04-23* Doesn’t show the bottom row of buttons on my iPhone 12 mini ### 3/5 — Not good for scientific notation *2025-02-15* I noticed when entering scientific notation, this app will not let me enter a negative exponent. When I press the change sign key nothing happens. A little problematic when doing computations involving scientific notation. Everything else the calculator works fine. This one issue is why I gave you only 3 stars instead of 5. **Developer response:** This is not a bug but rather the faithful simulation of the earliest HP-35, which you see when the calculator is set to "Vintage" and version "v1". According to the Operating Manual: E EX "causes no visual change in the display." In addition, "CH S must immediately follow E EX, otherwise CH S is ignored." This odd behavior was fixed by HP in later versions of the calculator. ### 3/5 — Needs an update *2022-04-18* Have been using this emulator for a couple years and was really happy with it until this last iPhone software update. The display is now chopped off at the bottom so is really unusable. Hope this gets fixed. ### 3/5 — Nice, but poor key touch *2017-11-17* I’ve had HP35s for 45 years & my 3rd one quit working so it’s great to have a substitute. This looks and works just like the real thing, however I’m very disappointed in the touch. Touch area of the keys is so small that I have to enter numbers very slowly, sometimes having to click multiple times to get a key to fire. I’ll be using another rpn calc that has better input even though I paid for this one. Too bad, I really liked this one otherwise. (Using this on an iPod 6.) ### 5/5 — Niche Calculator But Cool *2025-08-25* I love this app. I’m a geek for old school quirky devices. This one hits right at home. I use it as my main calculator on the phone. It’s not a calculator for everyone, but if you want the experience I recommend it. Been using this for quite some time. ### 5/5 — Hurra ! *2025-05-15* Das schnellere Einschalten war eine gute Idee - hm darauf habe ich l a n g e gewartet...! ### 5/5 — Great app *2024-12-22* Great simulator. However the LED display is a little dim. ### 5/5 — Simply the best *2024-10-31* Very fairly priced and perfectly designed and developed app. A master piece from the best. ### 5/5 — Ideal ! *2023-03-15* I love my original HP-35. But I can’t take it everywhere so it’s great to have this simulator on my phone or iPod. ### 5/5 — great memories *2023-01-12* I saved a long time while I was in high school in the 70s to buy one of these. IIRC it was $400. I finally got it and tried every formula I knew, it was fantastic. I went on to Purdue as an EE student and used this one to win an HP45 in their annual Calculator Olympics. Then I used that one to win an HP67. The next year they banned me from entering - the best honor of all. Unfortunately I don’t have them any more but this app fills that old desire perfectly. Thanks for the memories, CuVee, very well done. ## Most praised reviews (4 highest-rated) ### 5/5 — Extremeley pleasing HP-35 experience *2022-06-11* I'm using this on an iPhone 11 Pro Max. The ergonomics of the HP-35 — e.g., the number, size, and placement of buttons — really shine with this app and this screen size. Holding up an actual HP-35 and the app, you can even appreciate the lineage which goes all the way back to Steve's cold call to Bill Hewlett. ### 5/5 — Love this emulation! *2021-11-23* I’m almost irrationally happy with this app. The HP-35 was my first calculator, purchased in 1975 while I was a Chem major in college. I spent the previous years using slide rules and trig table. I was fascinated by the RPN entry and how it could generate trig values on the fly. I’d still have it if it hadn’t been stolen. Sad. Because they didn’t steal the charger too. So they played with it till the batteries ran down then it became a small brick. I am a university professor now and I just used this emulation to total test scores! How fitting! Thanks so much for this emulation!!! I am grateful. ### 5/5 — RPN-35 SD *2019-03-09* This is an excellent implementation of the classic, award-winning HP 35 calculator which was introduced in 1972 for $395. I love it! Well-done Cuvée! Please write an app for the HP-80 calculator. ### 5/5 — Terrific!... *2018-03-11* Great emulation of the original classic HP calculator. If you love these old calculators, check out the CuVee apps... --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-26.*