TradeFirst Subtraction for iPad & iPhone
This app can be used to teach and study the tradefirst 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 custom and random subtraction problems with small and large numbers. The number of digits in the numbers can be set.
The tradefirst method
The tradefirst subtraction method is similar to the traditional column subtraction method. The method has two stages. All of the "trading" or "borrowing" is done first. Then the subtractions are solved. This gives the method it's name, "tradefirst."
In the Everyday Mathematics curriculum the tradefirst method is the focus algorithm for subtraction.
Easy to use
The numbers are aligned automatically so that you can concentrate on solving the operations for each column.
Borrowing 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.
Settings
 Each number can have from 2 to 5 digits
 Problems can be custom or random
 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
 The lines separating the columns can be hidden
 Custom interfaces for iPad and iPhone
TradeFirst Subtraction Videos
Tradefirst subtraction with three digit numbers993  895

Tradefirst subtraction with five digit numbers89435  66598

TradeFirst Subtraction 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.