Modular Arithmetic

A calculator for arithmetic modulo N.  It lets you choose a fixed modulus, and then make lots of calculations without having to press a "mod" button again and again.  It also: 
  • supports fast modular division and exponentiation;
  • follows the order convention;
  • supports arbitrarily large numbers;
  • can show a full transcript of your calculation.
For details, screenshots and examples, see the App Store.

For support or suggestions, contact the author at burton.bab at

Who wrote this?

Benjamin Burton.  By day I do research in computational geometry and topology at The University of Queensland (see my university site).  I currently play with iOS programming in my spare time.

Why this app?

It was something I wanted myself - to fix a modulus and then make lots of quick calculations.  It is useful, for instance, in classical cryptography where you work consistently modulo 26 (if you are using the English alphabet).

Was it written carefully?

Yes - I very much care about correct results!  The code is backed up by a thorough suite of automated mathematical tests.

Is anything else planned?

For the hard-core computational topologists: I have also made Regina available (for free) on the iPad.  This is a large and complex body of software, and I am very happy to receive any feedback that may help with future releases.

Privacy policy

This app does not collect any data.


App Store