Hexagonal Number Calculator

How it is calculated

Enter the position n in the sequence (a whole number, 1 or more). The tool computes H(n) = n × (2n − 1), which is the same as 2n² − n. Both factors are plain integers, so the answer is exact and shown with thousands separators. Positions that are zero, negative or not whole numbers (such as 2.5) return no result, because a hexagonal number only exists for n = 1, 2, 3 and so on. Very large n works too, since the result is just a product, but it grows quickly: roughly twice n squared.

Common mistakes

• Counting from zero: the first hexagonal number is H(1) = 1, so n = 6 gives 66, not the value you would get by treating the list as starting at index 0.
• Using the formula for a different polygon, for example n(n + 1)/2 (triangular) or n² (square), when the task asks for hexagonal numbers.
• Typing a fraction or zero for n and expecting a value; only positive whole positions are accepted.
• Forgetting the brackets and computing n × 2n − 1 instead of n × (2n − 1), which is off by n − 1.