10thtriangularnumber

<-- Enter triangular number statement
  

Calculate triangular number 10

The formula for triangular number n is as follows
Tn  =  n(n + 1)
  2

Given n = 10, we have:
T10  =  10(10 + 1)
  2

T10  =  10(11)
  2

T10  =  110
  2

T10 = 55