Comparison

RPN vs PDF Flatten

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

RPN

This app emulates the first pocket scientific calculator, offering a photo-realistic vintage experience. It simulates original operating speeds and unique arithmetic bugs, with optional modern enhancements like non-volatile registers.

Highlights
  • 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
Features
Read full description

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

About

PDF Flatten

Features
Read full description

Turn fillable PDF forms into static, non-editable PDFs fully offline. PDF Flatten converts interactive PDF forms (AcroForms) into static documents that can no longer be edited. Perfect for official forms, contracts, and secure document submissions. No subscriptions. No accounts. No uploads. Everything is processed directly on your device. Why use PDF Flatten? • Convert fillable PDF forms into static PDFs • Remove interactive fields permanently • Works offline and fully private • No watermark • Fast native performance • Simple and clean interface Perfect for: • Contracts and agreements • Business forms • School documents • Applications and paperwork • Any fillable PDF form How it works: 1. Select a fillable PDF 2. Tap Flatten 3. Save or share your static PDF That is it. Your documents never leave your phone. Simple. Secure. Offline.

Screenshots

RPN4 screens
PDF Flatten3 screens

Verdict

The call

The clearest difference is chart position: PDF Flatten at #198 against RPN's unranked. PDF Flatten also leads on price ($0.99 vs $1.99). RPN's advantage is iOS requirement (12.0 vs 15.1). On ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

RPN costs $1.99 and PDF Flatten $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Scorecard3 real differences · 8 level
RPN versus PDF Flatten: the parameters behind the verdict, then further details
ParameterRPNPDF Flatten
Price$1.99$0.99 — better
Rating4.4 (14 ratings) — better—
Positive reviews71.4% of reviews—
Number of ratings14 — better—
Update frequencyEvery 6 months—
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
Best chart rank—#198 — better
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS12.0 — better15.1
Further details — not scored
Size14 MB29 MB
Age rating4+4+
DeveloperCuVee SoftwareStudyBridge LLC

In-app purchases

None

RPN

No in-app purchases

None

PDF Flatten

No in-app purchases

Questions

Is RPN free?
RPN costs $1.99, with no in-app purchases.
Is PDF Flatten free?
PDF Flatten costs $0.99, with no in-app purchases.
Do RPN or PDF Flatten have ads?
Neither RPN nor PDF Flatten shows ads.

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