The Column Subtraction app for iPad & iPhone
The Column Subtraction app allows you to teach and study the column subtraction method by solving random and custom subtraction problems.
Easy to use
The numbers are aligned automatically so that you can concentrate on solving the operations for each column. Pressing the borrow-button carries out borrowing which is animated step by step so you can see what happens. Borrowing over several columns is also supported.
After you solve the operation for each column the correct answer will fly to the right place. If the user presses the wrong button the answer will appear above the keyboard but it will not move.
Use random problems or input your own numbers
You can let the app pick the problems for you or you can input your own numbers.
Feedback and requests for new features
Please give feedback about this program.
Review by professor Tim Pelton
Tim Pelton, assistant professor of Mathematics Education at the University of Victoria:
"As a parent I like the potential that this Column Subtraction app has to help my child to master the traditional subtraction algorithm, but I have some caveats and suggestions to add to my recommendation. I urge you (parents/tutors/teachers) to support your children as they use this app and confirm that your child is understanding the process, that they are able to efficiently estimate and check the results and that they are able to visualize an appropriate context for the mathematical expression."
Professor Tim Pelton,
"If your goal is to help your child to master the traditional subtraction algorithm then Column Subtraction may be the ideal App."