for iPad and iPhone
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
Opposite-Change Addition with 3-digit numbers
816 + 109
Opposite-Change Addition in the Apple VPP Store for Education
The Volume Purchase Program allows participating educational institutions to purchase iDevBooks math apps in volume and distribute them to students. All iDevBooks math apps offer special 50% discount for purchases of 20 apps or more for participating educational institutions.