What is the formula in finding triangular numbers?

The formula for finding the nth triangular number is given by ( T_n = \frac{n(n + 1)}{2} ), where ( n ) is a positive integer. This formula calculates the total number of dots that can form an equilateral triangle when arranged in a triangular pattern. For example, the 3rd triangular number is ( T_3 = \frac{3(3 + 1)}{2} = 6 ).