iPhone Giveaway of the Day - Column Subtraction

This math app can be used to teach and study the column subtraction method. The app is easy to use and it has an intuitive interactive interface with customizable colors and other settings. The user can solve random or custom subtraction problems with small and large numbers. The number of digits in the numbers can be set. The column subtraction method is also known as columnar subtraction, long subtraction or longhand subtraction.

Easy to Use:
The numbers are aligned automatically so that you can concentrate on solving the operations for each column. Pressing the rename-button carries out renaming which is animated step by step so you can see what happens. You can also solve each step during the renaming by setting automatic renaming to off in the settings. Renaming 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.

25 Six-piece Jigsaw Puzzle: The puzzles are pictures of cute animals. Every time the user solves one addition problem, he will see one more piece of a six-piece picture puzzle. The picture puzzle feature can be turned off and on at any time.

The App has the Following Features and Settings:
-The number of numbers to subtract can be 2 or 3
-Each number can have from 1 to 5 digits
-Problems can be random or custom
-Renaming can be done manually or automatically
-Renaming can also be called regrouping, trading or borrowing
-The current operation for each column can be hidden
-The operands of the current operation can be highlighted
-Colors of the interface can be changed
-The speed of the animations can be set
-25 6-piece jigsaw puzzles of animals are shown one piece at a time
-The jigsaw puzzles can be hidden
-Different interface on iPhone and iPad
-Works in portrait and landscape orientation on the iPad