0
Wiki User
25
3
Sum = 79*(79+1)/2 = 79*80/2 = 3160
5050
87
if (n%2==0) sum=n/2*(n+1); else sum=(n+1)/2*n;
The sum of -1 and -2 is -3.
41
The sum of 2/9 and 1/3 is 5/9
1+2+3+4.....+100 = 101*50= 5050
81*82/2= 3321