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From Esa Helttula:
This app can be used to teach and study subtraction using the same-change rule. The app is easy to use and it has an intuitive interactive interface with customizable colors and other settings. The user can solve random subtraction problems. The Same-Change Rule in Subtraction If you subtract or add the same number from both parts of a subtraction problem, the results remain the same. In this way a subtraction problem 667 289 is easier to solve as 678 300. In the Same-Change Subtraction app the user can keep adding or subtracting the same number from both part of the subtraction until the subtraction problem can be solved easily. In the Everyday Mathematics curriculum the same-change rule method is one of the algorithms for subtraction. The App is Easy to Use The numbers are aligned automatically so that the user can concentrate on solving the operations for each column. The app has the following settings: -The numbers can have 2 or 3 digits -The current operation can be hidden -Colors of the interface can be changed -The speed of the animations can be set Video of the app You can see a video of the Same-Change Subtraction app in action at my site idevbooks.com. Feedback and Requests for New Features I have made this app to be a useful teaching and learning tool for those children and parents that use the Everyday Mathematics curriculum. New ideas to make this app better are welcome. Please give feedback at iTunes or visit my site idevbooks.com and give feedback there about this application. Please tell me if you have any ideas for new features.