Butler’s Apps

Application Development for iPhone, iPad, and iPod touch

Killer Aid: Killer Sudoku Combination Calculator

By Trevor Butler of Butler's Apps

A suite of tools to help solve Killer Sudoku puzzles

Killer Aid App

iPhone® and iPod touch® versions

iPad® version


If you've struggled to complete tricky, tough, or deadly Killer Sudoku puzzles then this App could be for you. It provides a suite of tools to aid finding the minimum number of combinations that add up to each cage’s sum. The results are clearly displayed with any duplicate numbers highlighted in red.

The target number of cells and their sum is entered using the edit tool. This presents a pick list of cells and sums values to simplify their selection and prevent invalid entries.  It is also possible to select the display of combinations with duplicate values.

Filter tools help reduce the possible combinations. Three variants of filter are provided namely:

  • Exclude
  • Include AND
  • Include OR

The exclude filter removes any combinations that contain the specified numbers. The "include AND" filter reduces the combinations down to those that include all the specified numbers. The "include OR" filter facilitates including combinations that contain one or more of a set of numbers. These three filter types can be combined together. Cage combinations can also be manually deleted.

A calculator tool, optimised for solving Killer puzzles, is provided. This helps with some of the solving strategies (e.g. determining the sums of  “innies” and “outies”  - remainders inside and outside the a 3 x 3 square, row or column). The calculator includes formula text to keep track of entries.

Lastly a support menu provides access to help, Killer Sudoku solving strategies and references sources of Killer Sudoku puzzles.


Dynamic type fonts are used for the "Cells", "Sum" and "Results" fields. The size of these fonts can be changed using the devices Settings tool. Either the following:

  • "Display & Brightness/Text Size"
  • "General/Accessibility/Larger Text"

Further Information


Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch. This app is optimised for iPhone 5, iPhone 6, and iPhone 6 Plus.


Apple, the Apple logo, iPhone, iPad and iPod touch are trademarks of Apple Inc., registered in the U.S. and other countries. App Store is a service mark of Apple Inc.



© Butler's Apps 2017