Hexagonal numbers are a type of figurate number that represent a hexagon. They can be calculated using the formula n(2n - 1) , where n is a positive integer. The first few hexagonal numbers are 1, 6, 15, 28, and 45. Each number corresponds to a hexagon that can be formed by arranging dots in a hexagonal pattern. These numbers are closely related to other figurate numbers, such as triangular numbers and pentagonal numbers. Hexagonal numbers also appear in various mathematical contexts, including combinatorics and number theory, where they help in understanding patterns and relationships among numbers.