Polygonal number

In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots are thought of as alphas (units). These are one type of 2-dimensional figurate numbers. In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots are thought of as alphas (units). These are one type of 2-dimensional figurate numbers. The number 10 for example, can be arranged as a triangle (see triangular number): But 10 cannot be arranged as a square. The number 9, on the other hand, can be (see square number): Some numbers, like 36, can be arranged both as a square and as a triangle (see square triangular number):