Number Rack

Number Rack

Slide beads to show and work with numbers and think in groups of 5s and 10s. 

App Tutorial

Learn all about this app with a set of fun challenges for teachers and students.

Number racks (also known as rekenreks) facilitate the natural development of children’s number sense. In the Number Rack app, rows of movable, colored beads encourage learners to think in groups of 5s and 10s, helping them to explore and discover a variety of addition and subtraction strategies. Display up to 10 rows, each with 10 beads, to work with numbers up to 100.

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.

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

App Features

  • Slide beads one-by-one or in groups across a row.
  • Display 1 to 10 rows of beads, 10 beads per row.
  • Reverse the colors of rows 6 to 10 to distinguish (or not) groupings of 25 beads.
  • Hide and reveal beads with resizable covers to pose problems and play games. 
  • Share your work by saving an image or creating an 8-character code and link to send to others.

Get More From This App

Book for Educators

The Learning to Think Book Series: The Rekenrek

This book offers teachers the theoretical basis and practical knowledge to employ the number rack, or rekenrek, as a powerful mathematical tool. Building on the idea that children must be able to “see” numbers within other numbers (for example, 7 might be thought of as “5 plus 2 more”), the number rack 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.


 Download English  Download Spanish

Supplemental Activity Book

Supplemental activity book, part of the Learning to Think Mathematically with Rekenerek series.

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 including cardinality, one-to-one relationships, part-part-whole relationships, and subitizing.



Activity Book

Using the Rekenrek as a Visual Model for Strategic Reasoning in Mathematics -- a supplemental 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" x 3"
  • 2 black pipe cleaners
  • 10 red beads
  • 10 white beads
  • 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.

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This app was crafted by Clarity Innovations: “We improve teaching and learning by creating solutions that match promising technologies with the needs of education.”