What's New

- support for iOS 15

App Description

This math app can be used to teach and study the partial differences 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 subtraction problems. The number of digits in the numbers can be set.

Endorsed By Teachers

R. Zeni, Ecole Sandy Hill Elementary, Abbotsford, BC, Canada:

"The math apps by Esa Helttula allow students to practice and reinforce the specific computation strategies taught in class, with as much or as little scaffolding as necessary. They also provide individualized feedback to each student, with an immediacy that is not always possible through pencil and paper practice. Being able to adjust the level of difficulty to suit their needs is also very motivating for the students. I am so glad to have come across this great educational tool!"

More endorsements from teachers can be seen at my site: idevbooks.com.

The Partial Differences Subtraction Method

The partial differences subtraction method is a two-step process. In the example 936 - 580, each place value is first subtracted separately from left to right. The partial differences are added and 400 - 50 + 6 produces the answer 356.

In the Everyday Mathematics curriculum the partial differences 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.

After you solve the operation for each column the correct answer will fly to the right place. If you press the wrong button the answer will appear above the keyboard but it will not move.

Settings:

- Each number can have from 2 to 3 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

Other iDevBooks math apps

iDevBooks math apps have been reviewed and endorsed by Wired.com, IEAR.org, Edudemic.com, Teachers with Apps, and other respected sites and organizations.

Some of the other 40 iDevBooks math apps are Column Addition, Long Multiplication, Long Division, Column Subtraction, Visual Multiplication Table, Partial Quotients Division, Partial Products Multiplication, Partial Sums Addition, Decimal Rounding, etc.

Feedback and requests for new features

New ideas to make this app better are welcome. Please visit idevbooks.com to give feedback.

Privacy

This app has no ads or in-app purchases and it does not transmit any data during the operation of the app. This app also does not contain any links to other apps or the web.

iPhone Screenshots

(click to enlarge)

Partial Difference Subtraction screenshot 1 Partial Difference Subtraction screenshot 2 Partial Difference Subtraction screenshot 3 Partial Difference Subtraction screenshot 4 Partial Difference Subtraction screenshot 5

iPad Screenshots

(click to enlarge)

Partial Difference Subtraction screenshot 6 Partial Difference Subtraction screenshot 7 Partial Difference Subtraction screenshot 8 Partial Difference Subtraction screenshot 9 Partial Difference Subtraction screenshot 10

App Changes

  • June 24, 2011 New version 1.3
  • August 13, 2011 Price decrease: $3.99 -> $1.99
  • August 27, 2011 Price increase: $1.99 -> $3.99
  • September 22, 2011 New version 1.4
  • October 01, 2011 Price decrease: $3.99 -> FREE!
  • October 04, 2011 Price increase: FREE! -> $3.99
  • January 31, 2012 New version 2.0
  • February 07, 2012 New version 2.1
  • August 09, 2012 Price decrease: $3.99 -> $2.99
  • August 23, 2012 Price increase: $2.99 -> $3.99
  • June 23, 2013 New version 2.2
  • October 16, 2013 New version 2.3
  • August 12, 2014 Price increase: $3.99 -> $5.99
  • August 13, 2014 Price decrease: $5.99 -> $3.99
  • September 14, 2014 New version 3.0
  • December 31, 2014 Price increase: $3.99 -> $4.99
  • March 06, 2015 Price decrease: $4.99 -> $3.99
  • August 21, 2015 Price decrease: $3.99 -> FREE!
  • August 23, 2015 Price increase: FREE! -> $3.99
  • July 11, 2016 New version 4.0
  • November 25, 2016 Price decrease: $3.99 -> FREE!
  • November 27, 2016 Price increase: FREE! -> $3.99
  • June 15, 2019 New version 5.2
  • September 30, 2019 New version 6.0
  • September 19, 2023 New version 6.5