In the Opposite-Change Addition app the user can keep adding a number to one addend and subtract the same number from the other addend until the addition problem can be solved easily.

The opposite-change rules states that if you subtract a number from one addend and add the same number to the other addend, the sum remains the same. An addition problem 267 + 289 is easier to solve when it has been changed into 256 + 300.


- The numbers can have up to 3 digits
- You can set your own problems
- Three different themes
- Native interfaces for iPhone, and iPad
- Open worksheets of up to 10 problems that are made on the site

Other iDevBooks math apps

iDevBooks math apps have been reviewed and endorsed by, Common Sense Media, and other respected sites and organizations.

Some of the over 30 other iDevBooks math apps are Visual Multiplication Table, Decimal Rounding, Whole Number Rounding, Column Subtraction, Column Addition, Long Division, Long Multiplication, Lattice Multiplication, Fraction Math, Partial Differences Subtraction, Partial Quotients Division, Partial Sums Addition, etc.

Feedback and requests for new features

New ideas to make this app better are welcome. Please visit to give feedback.


This app has no ads or in-app purchases and it does not transmit any data during the operation of the app. This app also does not contain any links to other apps or the web.

What's New

Version 5.0

- open worksheets from app (new worksheets can be made on the site)
- support for iOS 10.0
- support for shared iPad in school environments

For more information about worksheets and other new features of this version please visit Please also get in contact if you have any feedback or you want information about 32 iDevBooks math apps.


Esa Helttula
2.9 MB
Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© Esa Helttula


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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