Free iOS App – Door 24 Plus (Math)


Door 24 Plus is a math fluency app that harnesses the power of game design to help develop students’ skills in both fact fluency and computational fluency. It provides targeted practice in the use of basic facts, number sense, and algebraic thinking. 

Students will have the chance to play one of two games depending on their level:
• Snargg Splatt develops fact fluency
• Victor Fixer develops computational fluency

Door 24 Plus is part of i-Ready, an award-winning online program published by Curriculum Associates. Learn more about i-Ready at

Fact Fluency game (Snargg Splatt)
• Fact fluency practice with all 4 operations
• Options for reviewing facts in an instructional sequence
• 2-player version for collaborative play
• i-Ready users can log in to the app and save their data across devices

Computational Fluency game (Victor Fixer)
• Provides practice in computational fluency across five grade levels, from grades 4 – 8 with content available for students who are working a level behind.
• Multiple sets of problems with increasing difficulty so that students slowly work their way up.
• Bonus activities require students to find all possible solutions to expand their problem solving skills.
• Includes scaffolded hints and Math Review screens to help students when they struggle.
• i-Ready users can log in to the app and save their data across devices.

Fact Fluency (Snargg Splatt)
• Fluency with addition facts from 0 to 20
• Fluency with subtraction facts from 0 to 20
• Fluency with multiplication facts from 1 to 144
• Fluency with division facts from 1 to 144

Computational Fluency (Victor Fixer)
• Apply number sense and algebraic thinking
• Represent numbers in multiple ways
• Understand the concept of equivalency
• Apply concepts of factors and multiples
• Use parentheses in numerical expressions
• Apply the order of operations
• Create and evaluate numerical expressions
• Add, subtract, multiply, and divide with negative numbers
• Evaluate square roots and cube roots
• Understand and apply properties of integer exponents

Math standards propose a balanced approach to math and stress the goals of conceptual understanding, fluency, and application. Door 24 Plus focuses on establishing a foundation based on fact fluency and then building computational fluency by providing practice that requires students to solve problems using basic facts, number sense, and algebraic thinking. 

Being able to automatically recall facts will help students free up working memory and allow them to concentrate on more challenging math tasks. For example, spending time counting on fingers to work out an addition or subtraction problem can be an impediment to working on higher-level math skills. Additionally, by having math fact fluency, students will be more confident which can lead to greater gains later on.

The Principles and Standards for School Mathematics (NCTM 2000) state: “Students exhibit computational fluency when they demonstrate flexibility in the computational methods they choose, understand and can explain these methods, and produce accurate answers efficiently.”

Door 24 Plus addresses each of the three facets of computational fluency: 
• Accuracy: Students use number facts, order of operations, and number relationships to create expressions that are equivalent to 24 
• Efficiency: Students learn to use strategies that are easily practiced such as making tens, recognizing factors of 24, thinking of an expression as a single quantity, understanding relationships between operations, etc.
• Flexibility: The Challenge set in every level requires students to find as many expressions as possible that are equivalent to 24 given a particular number set. Students also need to be flexible in choosing an appropriate strategy or strategies based on the problem at hand.

Phone: 800-225-0248
M – Th 8:30am – 7pm EST
Fri 8:30am – 5pm EST


Nathan Smith

Nathan Smith is Director of Technology for the College of Education and Human Services at Utah State University. In that role, he also directs The Adele & Dale Young Education Technology Center (The YETC) located in room 170 of the Education Building on Utah State University's Logan campus. The YETC is a combination student open­access computer facility, a K­12 curriculum materials library, a NASA Educator Resource Center for Utah, and a technology training center. Nathan served eight years (2004­2012) on the Board of Directors for the Utah Coalition for Education Technology (UCET) He was re­elected in 2014 to serve another two year term on the board. A former elementary school teacher, Nathan has taught students every age from young children to senior citizens. He has had the opportunity beginning in 2011 to train international high school teachers from all over the world about technology in education, through the U.S. State

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