The Office Discipline Referra application's logo which is a wooden board with the letters O.D.R routed into it.

Terrific Triangle

Build creative equations while practicing math facts


A math facts  drill-and-practice program that teaches fact families for both addition/subtraction and multiplication/division.
What it does:   The triangle presents two parts of a fact family and the player must determine the missing third part. The sum and product always appear at the top of the triangle. The addends and factors always go in the two lower corners.
Free:   There are no in-app purchases or advertisment banners.

Screen Shots

A thumbnail of a portrait Android phone displaying an addition / subtraction problem against a timer in the Terrific Triangle app. A thumbnail of a landscape Android phone showing a multiplication / division problem against the timer in the Terrific Triangle app.
A thumbnail of a portrait Android phone showing the preferences screen for the Terrific Triangle app. A thumbnail of a landscape iPad displaying an addition / subtraction screen (with timer)from the Terrific Triangle app.


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System Requirements

iOS 12.x or later
For iPhone, iPod touch, and iPad
Android 5.1 (Lollipop) or later
MacOS 10.9 (Mavericks) or later
Windows 7 or later


  • version 1.3.2  August 2020         improves keypad entry and provides better feedback for correct answers.

  • version 1.3.0  August 2019 - Added support for Android. Mac version is now 64-bit. Both Mac and Windows versions are now code signed.

  • Originally written for Mac OS in 2003 by Scott Morrow for use in his third grade classroom as a supplement to the Everyday Mathematics program (SRA / McGraw-Hill.) Rewritten in 2018 for use on iPads in his second grade classroom.

  • Written with Livecode   green LiveCode programming language icon
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