Trade-First Subtraction

This app can be used to teach and study the trade-first 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 trade-first method

The trade-first 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, "trade-first."

In the Everyday Mathematics curriculum the trade-first 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

Trade-First Subtraction Videos

Trade-First 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.

Trade-First Subtraction in the VPP store