Comparison

RPNu vs isPrime?

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

Head to head
About

RPNu

Features
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RPNu is a calculator that makes crunching numbers easier than it’s algebraic equivalent. RPN stand for Reverse Polish Notation (The β€˜u’ stands for universal, meaning it runs on both the iPad and iPhone.) and is the numeric evaluation method used for this app. RPN, I feel, is far superior to the algebraic method and once learned you will never want to use the algebraic again. This calculator has all the normal mathematical function, but also contains a host of other functions that you may find very useful. Space is limited in this description but here are the highlights: Help: There is extensive help to aid the user in determining how to use this app. It is also context sensitive. Programable: You can write your own programs and there are many tools to aid you in doing this. Graphics: You can graph equations and there are several modes to cover almost all requirements. A universal converter that you will find very useful. Matrix arithmetic (determinate, invert, add, subtract and multiply). Date calculator and an hours calculator with moon phase display. Elements and periodic table information. Combinations and permutations calculator Equation integration and root finder. Amortization with many useful functions. Mapping function that allows you to determine distance between points and other functions. Hyperbolic functions. Hexadecimal, Octal, and Binary modes. Barometer function showing QNE and QNH. A compass that not only shows magnetic and true north, but also shows the address you are at. This app includes extensive support for a Bluetooth keyboard. Also, extensive support is given to export your calculations to either email or the universal clipboard.

About

isPrime?

Features
Read full description

It's a fast prime number checker.

Screenshots

RPNu4 screens
isPrime?4 screens

Verdict

The call

The clearest difference is update cadence: RPNu at every 2 months against isPrime?'s every 16 months. On price, ads, in-app purchases and device support there is nothing between them.

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

CostPrice Β· In-app purchases Β· Ads Β· Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

RPNu ships an update every 2 months, isPrime? every 16 months. The most recent releases landed on October 26, 2026 and October 25, 2026 respectively.

Scorecard1 real difference Β· 5 level
RPNu versus isPrime?: the parameters behind the verdict, then further details
ParameterRPNuisPrime?
PriceFreeFree
Update frequencyEvery 2 months β€” betterEvery 16 months
AdsNoNo
In-app purchasesNoNo
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.015.0
Further details β€” not scored
Size49 MB4 MB
Age rating4+4+
DeveloperScott JohnsonOmer Faruk Mesebuken

In-app purchases

None

RPNu

No in-app purchases

None

isPrime?

No in-app purchases

Questions

Is RPNu free?
RPNu is free to download, with no in-app purchases.
Is isPrime? free?
isPrime? is free to download, with no in-app purchases.
Do RPNu or isPrime? have ads?
Neither RPNu nor isPrime? shows ads.
Which is updated more often, RPNu or isPrime??
RPNu ships an update every 2 months, and isPrime? every 16 months. Most recently, RPNu was updated on October 26, 2026 and isPrime? on October 25, 2026.

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