# RPN-35 SD — First scientific calculator!

> Emulation of the first pocket scientific calculator with vintage and enhanced modes. (iPhone/iPad app by CuVee Software.)

- Source: https://appshunter.io/ios/app/rpn-35-sd/id956224485 (this page in markdown: same URL + `.md`)
- Developer: [CuVee Software](https://appshunter.io/developer/424873503)
- Category: Productivity, Utilities
- Price: $1.99
- Rating: 4.40/5 from 14 App Store ratings · 14 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 14 MB
- Languages: American English
- Released: 2015-01-18
- Data updated: 2026-08-26
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/rpn-35-sd/id956224485/reviews.md

## What is RPN?

On January 4, 1972, Hewlett-Packard announced the HP-35, world's first scientific calculator small enough to fit in a pocket - more precisely, Bill Hewlett's shirt-pocket. The HP-35 was an immediate hit with students, engineers, and scientists. Despite its steep price of $395 (about $3000 today), it sold ten times better than anticipated in the first year.

Experience this unique calculator that won HP the prestigious "IEEE Milestone in Electrical Engineering and Computing" in 2009.


Features:

• Photo-realistic look-and-feel
• Three skins: version 1, versions 2 & 3 (1973) and final version 4 (1974)
• Vintage mode and Enhanced mode
• Key-click and key-glow, both optional
• Swipe left across display to correct number input errors
• Cut/copy/paste display value
• Display stack registers and memory registers
• All decimal points but one light when iPhone battery charge drops below 5%


Vintage mode
In this mode, peculiarities of a real HP-35 are simulated:
- original speed of operation
- stack register Z copied to T on trig functions
- leading zeros may be entered; zero can be made negative
- a negative number may be entered by pressing CHS before or after the number
- a keyboard entry or RCL immediately following STO does not raise the stack
- for version 1 only: simulation of a number of known arithmetic bugs

Enhanced mode
- non-volatile stack and registers
- use registers 1 through 9 with HP-45-like register arithmetic
- register 0 works as LastX register

## Key features

- Photo-realistic look-and-feel
- Multiple vintage skins
- Vintage and Enhanced modes
- Optional key-click and key-glow
- Swipe to correct input
- Display stack and memory registers

## Recent user reviews (10 of 14)

All indexed reviews: https://appshunter.io/ios/app/rpn-35-sd/id956224485/reviews.md

### 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...!

### 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.

### 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.

### 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.

### 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.

## Frequently asked questions about RPN

### What is RPN-35 SD?

RPN-35 SD is a mobile application that emulates the HP-35, the world's first pocket scientific calculator. It offers a photo-realistic experience with both vintage and enhanced modes.

### Does RPN-35 SD have ads?

No, RPN-35 SD does not contain advertisements. It is a paid application with no in-app purchases or ads.

### What devices does RPN-35 SD support?

RPN-35 SD is supported on iPhone and iPod devices. It is available for download on iOS.

### How much does RPN-35 SD cost?

RPN-35 SD is a paid application priced at $1.99. This one-time purchase grants access to all its features.

### What are the vintage mode features in RPN-35 SD?

Vintage mode in RPN-35 SD simulates peculiarities of the original HP-35, including original speed, specific stack behavior on trig functions, and simulation of known arithmetic bugs for version 1.

### Can I correct input errors in RPN-35 SD?

Yes, RPN-35 SD allows you to correct number input errors by swiping left across the display. You can also cut and copy the display value.

### How often is RPN-35 SD updated?

The latest version of RPN-35 SD is 2.4, which was last updated on October 16, 2025. Updates are released periodically by CuVee Software.

### What is the age rating for RPN-35 SD?

RPN-35 SD has an age rating of 4+. This indicates it is suitable for users of all ages, with no mature content.

## Version history (last 5 releases)

### 2.4 — 2025-10-16

• Improved compatibility with iPhone Air and iOS 26.

### 2.3 — 2025-05-09

• Faster startup – no delay until the first button press is recognized after switching on.

### 2.2 — 2024-10-30

• Redesigned Settings screen

• Visual adjustments to iPhone 16 Pro and iPhone 16 Pro Max

• RPN-35 SD requires iOS 12 or later

### 2.1 — 2022-09-22

• Haptics
  – Set the haptic feedback level in the calculator's settings.
  – „Sounds & Haptics“ / „System Haptics“ must be on in the iPhone's settings.
  –  Note that iPads have no haptics engine.
  
• Optimized Settings View for devices with Home button

• Compatibility with iPhone 14 Pro

### 2.0.2 — 2020-11-05

Compatibility with iPhone 12

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## More apps by CuVee Software

- [RPN-45 HD](https://appshunter.io/ios/app/rpn-45-hd/id424873500)
- [RPN-70 HD](https://appshunter.io/ios/app/rpn-70-hd/id436127144)
- [Smart Sudoku](https://appshunter.io/ios/app/smart-sudoku/id457564906)
- [Vintage-45](https://appshunter.io/ios/app/vintage-45/id506402272)
- [RPN-45 SD](https://appshunter.io/ios/app/rpn-45-sd/id509923051)
- [RPN-67 NP](https://appshunter.io/ios/app/rpn-67-np/id603100249)

All apps by CuVee Software: https://appshunter.io/developer/424873503

## Related topics

[cuvee software](https://appshunter.io/ios/topics/cuvee-software)

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*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.*