Calculate Triangular Number

Calculator for the triangular number at a given place. A triangular number is the sum of consecutive natural numbers, starting at 1 (or at 0). The second triangular number is 1+2=3, the third is 1+2+3=6, the fourth triangular number is 1+2+3+4=10 and so on. The name is triangular number, because if you want to build an equilateral triangle with equal pieces, the number of pieces needed is a triangular number.
Please enter a natural number. The triangular number on this place will be calculated.

The formula for the n-th triangular number is n*(n+1)/2.

Example: the 27. triangular number is 378.