Adding triangular numbers

Table of Contents

• Triangular Numbers
• Adding Triangular Numbers
• Summary
• What’s Next?

In the previous segment, we learnt about the properties of square numbers. In this segment, we will look at triangular numbers.

What is a Triangular number?

A number whose dot pattern can be arranged as a triangle is a Triangular number. So the numbers, 3, 6, 10, 15 are some of the examples of triangular numbers.

1 3 6 1 1

Triangular numbers

Although number 1 is represented by a single dot, it is also considered a triangular number.

Adding triangular numbers

The sum of two consecutive triangular numbers is always a square number.

For example,

1 and 3 are consecutive triangular numbers.

1 + 3 = 4, which is a square number that is, its dot pattern is a square. And 2² = 4

1 3 4

Example 1

6 and 10 are consecutive triangular numbers.