X n nn12. The formula is usually written in the form n n12. Triangular numbers Triangular numbers are made by arranging dots to form either equilateral or right-angled isosceles triangles.
N 16.
Google triangular numbers to find this. The general formula of triangular numbers. Triangular numbers Triangular numbers are made by arranging dots to form either equilateral or right-angled isosceles triangles. Nth triangular number is the sum of n consecutive natural numbers from starting which is simply nn 1 2.