# PrimalityTest — Very Fast App

> App to build and test numbers for primality with incremental input. (iPhone/iPad app by Alberto Ragagnin.)

- Source: https://appshunter.io/ios/app/primalitytest/id1526376611 (this page in markdown: same URL + `.md`)
- Developer: [Alberto Ragagnin](https://appshunter.io/developer/1523888663)
- Category: Education, Reference
- Price: Free
- Rating: 2.00/5 from 1 App Store ratings
- Age rating: 4+
- Requires: iOS 13.6 · 2 MB
- Languages: English
- Released: 2020-08-09
- Data updated: 2026-07-07
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/primalitytest/id1526376611/reviews.md

## What is PrimalityTest?

Build your number adding the multiples of 1,2,3,4,5,6,7,8,9 or multiply for 10
so you can build your number and then check.

For example If I want text :  99499 I will type
+9 then x10 results 90
then +9 results 99 then x10 results 990 then +4 results 994 then x10
results 9940 then +9 results 9949 then x10 results 99490 then +9
results 99499. Leave in the feedback if you would prefer the standard input!
I will change everything in the next update!

Bug fixed with version next 1.0 :

+ ver. 1.1 fixed the  the false positive  bug "4 is prime"  ;
+ ver.1.1.1 fixed the bug that crashed the app, added an upper bound for big integer;
+ added the button N/M that allow two different ways of input :  N is normal like a standard calculator,  M is incremental.
+ 1.2 and 1.3 minor bugs fixed
+ 1.4. overflow for big integer typed with normal mode fixed.
+ 1.5 fixed the crashing bug after "pressing any button after primality test" .
 
About icon: the picture of the face took from a statue,
that represents  Eratosthenes.  
An ancient mathematician and philosopher 
tha made the first procedure to determinate primes from 0 to 100.
(look the Sieve of Eratosthenes ).

## Key features

- Build numbers using addition and multiplication
- Test numbers for primality
- Incremental input method (M)
- Standard calculator input method (N)
- Bug fixes and performance improvements
- Inspired by Eratosthenes


## Frequently asked questions about PrimalityTest

### What is PrimalityTest?

PrimalityTest is an application designed to help users construct numbers and then determine if those numbers are prime. It offers two distinct input methods for building numbers.

### How does PrimalityTest work?

You can build a number by adding multiples or multiplying, then the app checks if the final number is prime. It offers a standard calculator input (N) and an incremental input (M).

### What kind of numbers can I test with PrimalityTest?

The app allows for the creation of large integers, and has implemented an upper bound and overflow fixes for big integers typed in normal mode.

### Has PrimalityTest been updated recently?

The app was last updated on August 14, 2020, with version 1.9.5. Previous updates have focused on fixing bugs like false positives and app crashes.

### What is the learning methodology of PrimalityTest?

PrimalityTest focuses on practical application by allowing users to build and test numbers, indirectly teaching about prime number properties through hands-on interaction.

### Does PrimalityTest offer certifications?

This application does not offer certifications. Its primary function is to serve as a tool for exploring and testing prime numbers.

### Is PrimalityTest suitable for all ages?

PrimalityTest has an age rating of 4+, making it accessible for a wide range of users interested in mathematical exploration.

### What devices support PrimalityTest?

PrimalityTest is available on iPhone, iPad, and iPod devices, indicating broad compatibility within the Apple ecosystem.

## Version history (last 1 release)

### 1.9.5 — 2020-08-14

Extended the generation of primes to 9 digits
The Algorithm is faster and optimized

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## More apps by Alberto Ragagnin

- [RiskRollDicez](https://appshunter.io/ios/app/riskrolldicez/id1525568976)
- [MonMonMeal](https://appshunter.io/ios/app/monmonmeal/id1611222771)

All apps by Alberto Ragagnin: https://appshunter.io/developer/1523888663

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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 2026-07-07.*