Math CentralQuandaries & Queries


Question from Heather, a student:

I was wondering if there was an equation in order to calculate the number of blocks on the face of a pyramid.
For example:

  X X

Is there a specific formula in order to calculate that there are 6 blocks here?

Thank You,


Hi Heather,

These are called triangular numbers

Number of rows   Number of balls
1 triangular 1 1
2 triangular 2 3
3 triangular 3 6
4 triangular 4 10

If you go to the Quandaries and Queries page and use the Quick Search to search for the term triangular numbers you will see some previous questions we have answered on these numbers. You might find them all interesting but the one that answers your question is our response to a question by Stuart.

Harley Weston

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