Teaching Students About the Number of Dominoes in a Standard Set


Understanding the number of dominoes in a standard set can be both an educational and enjoyable activity for students. In this article, we will explore the concept of dominoes, delve into the mathematical principles behind counting them, and offer practical teaching strategies to engage students in this fascinating learning experience.

The World of Dominoes

Dominoes are rectangular tiles used to play numerous games worldwide. Each tile, also called a bone, is divided into two square ends with a line in the middle. One or both sides of a tile contain a number of pips or spots that indicate its value. The absence of any spots results in a blank end. A standard set of dominoes includes tiles representing all possible pairs of numbers (and blanks), from double-blank to double-six.

Mathematical Explanation

To calculate the number of dominoes in a standard set, we must use combinatorics—a branch of mathematics focused on counting and organizing objects. Specifically, we will use the formula for finding combinations: C(n+1, r) = (n+1)! / (r!(n+1-r)!)

In our case, n represents the highest value on a domino (6 in a standard set), and r is equal to 2 due to each tile having two ends.

Applying the formula:

C(6+1, 2) = 7! / (2!(7-2)!)

C(7, 2) = 7! / (2!5!)

C(7, 2) = 5040 / (2×120)

C(7, 2) = 5040 / 240

C(7, 2) = 21

Therefore, there are 21 unique combinations in which two ends can have numbers ranging from zero to six, including the blank end.

Teaching Strategies

Begin with a discussion about dominoes, their history, and their use in various games.

Introduce the concept of combinatorics and provide a brief overview of combinations and permutations. Use examples from daily life to make the concepts more accessible.

Show students a standard set of dominoes and encourage them to examine and count the tiles themselves. They can organize them into pairs as well.

Walk students through the mathematics behind calculating the number of dominoes in a standard set using the formula presented above.

Use visual aids to help students understand how each combination is formed and why it is essential to use maths in such a calculation.

Engage students in hands-on activities that allow them to explore different combinatorial problems involving dominoes. This can include games, puzzles, or designing their own unique sets.

Extend the lesson by introducing more advanced mathematical concepts such as probability and statistics in the context of domino games.


Teaching students about how many dominoes are there in a standard set encourages them to explore mathematical principles in an enjoyable and engaging way. By blending history, theory, and practical application, educators can create memorable learning experiences that will have lasting impacts on students’ understanding of combinatorial math and its real-world applications.

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