App review by Galen McQuillen, Common Sense Education | Updated January 2016
Number Rack, By The Math Learning Center
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Number Rack, by The Math Learning Center

Virtual abacus works just like the real thing, not as fun

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Learning rating
Community rating
Based on 1 review
Privacy rating
73%| Warning Expert evaluation by Common Sense
Subjects & Skills
Math, Critical Thinking

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Pros: Looks and feels like a physical abacus with responsive controls and familiar layout, while annotation features and variable rows add extra value.

Cons: Colors are fixed, there's no built-in lessons or guides, and there's no satisfying "click" when sliding beads around. Plus, use is totally reliant on teacher knowledge.

Bottom Line: It's a free, portable abacus that requires a good curriculum to make it useful. Otherwise it's just e-beads.

Incorporate Number Rack into your early counting and place-value lessons to add that great manipulative boost to otherwise tough cognitive jumps. Also, even older kids can benefit from the way it makes multi-digit addition and subtraction so real and present, in a way that carrying and borrowing in tabular arithmetic can't quite touch. 

Either way, you'd benefit from a good search for abacus lessons (search for "slavonic abacus", "bead-frame", "rekenrek," and "100-bead abacus" lessons) before jumping into classroom or one-on-one use, because without some support it's pretty tough to discover number properties just by playing around. If you've already got a physical version, go with that first; if you want every kid to have their own to work with, installing this on a class set of tablets would be a smart move. 

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Number Rack is a virtual slavonic abacus (also called a bead frame) with some extra features that make it a more flexible learning tool than the real deal. It features the familiar red and white beads (which can't be re-colored) and horizontal layout of the elementary school manipulative, and beads slide across the virtual rods effortlessly with smooth animation. Groups of beads can be dragged and positioned arbitrarily, just like the real thing.

Unlike the physical version, Number Rack lets users change the number of rows, from just one (to two if you need a 20-bead rekenrek), all the way up to the classic 10. It also includes an annotation tool so you can write notes and circle groups, and an equation editor for adding math right to the screen. There's a built-in shade so you can cover groups of beads in pre-set arrangements. 

The 100-bead abacus has a long history of elementary school use, and Number Rack's version will work just as well as that real-life learning tool. It's great for teaching place value, counting patterns, multi-digit operations, and grouping, to name just a few applications. This one doesn't have the wonderful hands-on feel and satisfying click-clack of physical beads, and there is some emotional, intuitive sense of number lost in the translation to a virtual tool, so don't chuck out your wooden model just yet.

The option to change colors to make it resemble a Montessori-style bead frame, or to color groups of beads arbitrarily for specialized lessons, would add extra value beyond the typical slavonic abacus uses. Also, even a little bit of support for kids and teachers about how to use this fairly specialized tool would be a welcome addition.

Overall Rating


A realistic design with wonderfully responsive controls make this virtual abacus almost as nice as the real thing, lacking only the tactile feel of beads clicking together. 


This kind of abacus is great for teaching place value and multi-digit operations, but that depends entirely on the skill of the teacher and the quality of the lesson. 


There's a nice tutorial of all the app's features and a link to to the developer's (paid) curriculum, but for students, there's no mathematical help to be found. Again, this is just a tool, not a complete learning experience.

Common Sense reviewer
Galen McQuillen Researcher

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Featured review by
Susan K. , Classroom teacher
Classroom teacher
Bishop Elementary School
Bishop, United States
A Virtual Abacus for the Internet Age
The Number Rack app worked really well in conjunction with instruction through the Bridges 2 curriculum. I would second the comments made by the app reviewer "'d benefit from a good search for abacus lessons (search for "slavonic abacus", "bead-frame", "rekenrek," and "100-bead abacus" lessons) before jumping into classroom or one-on-one use, because without some support it's pretty tough to discover number properties just by playing around" With a solid understanding of the purposes and procedure ...
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