Number Rack for iPad, Web, and More

The Number Rack (also known as Rekenrek) facilitates the natural development of children’s number sense. Rows of moveable, colored beads encourage learners to think in groups of fives and tens, helping them to explore and discover a variety of addition and subtraction strategies.

This virtual version of the manipulative is an open-ended educational tool, ideal for elementary classrooms and other learning environments that use laptops, iPads, or Chromebooks.

To purchase Student Number Racks, click here.

The Number Rack is a key component of Bridges in Mathematics, second edition. Online preview available.

App Features

  • Display 1 to 10 rows of beads, 10 beads per row.

  • Hide beads with resizable shades, which allows teachers or learners to model subtraction or difference problems.
  • Reverse the colors of rows 6 to 10 to distinguish (or not) groupings of 25 beads.
  • Enter text directly from your keyboard with the writing tool. Add labels, descriptions, or instructional text to your work.
  • Edit equations and other math text using a traditional text field.
  • Add drawings on the workspace to explain thinking.
  • Share your work by saving an image or url, or providing a sharing code to others. Great for creating the initial setup of an activity, then sharing it with students so they can explore it further.

Get more from this app

Book for Educators

This book provides educators with the theoretical basis, practical knowledge, and expertise to use a powerful mathematical tool called the Rekenrek. Building on the idea that children must be able to “see” numbers within other numbers (e.g., 7 might be thought of as “5 and 2 more”), this book helps children recognize number combinations of 5 and 10, develop a rich sense of numbers between 0 and 20, and build a powerful set of intuitive strategies for addition and subtraction of both single- and double-digit numbers.

Supplemental Activity Book

This compilation of student-ready activities builds upon the contexts and learning objectives in Learning to Think Mathematically with the Rekenrek (listed above). Students solve imaginable and accessible problems using the key mathematical principles accessed through the rekenrek model, including cardinality, one-to-one-relationships, part-part-whole relationships, and subitizing.

Activity Book

Ten activities along with an introduction to using the Rekenrek or Number Rack. Includes correlations to the Common Core State Standards.

Build Your Own Number Rack

Materials Needed

  • 1 piece of mat board, 6" × 3"
  • 2 black pipe cleaners
  • 10 red beads
  • 10 white beads
  • 4 strips of tape


Along the short side of the mat board cut two small notches one inch from each edge. Thread five white beads followed by five red beads onto each pipe cleaner. Place each pipe cleaner onto the front of the matte board and fold the ends into the notches and around to the back. Secure pipe cleaner ends with tape.


The Number Rack app was made possible by a generous donation from Dr. David Moursund.

Technical Support and Feedback

This app was crafted by Clarity Innovations: “We improve teaching and learning by creating solutions that match promising technologies with the needs of education.” For app support and feedback, contact them at

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