The answer is 25 but I do not know the rule. If someone else knows the rule feel free to edit my answer.
first thing i would like to tell that their no particular rule to solve this problem. But if we consider the working of calculator then the addition will be done as follows.
((((((((1+2)+3)+4)+5)+4)+3)+2)+1) = 25
(((((((3+3)+4)+5)+4)+3)+2)+1) = 25
((((((6+4)+5)+4)+3)+2)+1) = 25
(((((10+5)+4)+3)+2)+1) = 25
((((15+4)+3)+2)+1) = 25
(((19+3)+2)+1) = 25
((22+2)+1) = 25
(24+1) = 25
solve from innermost bracket towards outer
This is just a consideration of calculator if you solve through calculator the producer will look as above.
If any one knows any simple answer please feel free to continue this discussion.
Sum = 79*(79+1)/2 = 79*80/2 = 3160
if (n%2==0) sum=n/2*(n+1); else sum=(n+1)/2*n;
8/9
The answer would be positive 3.
There's a rule?
Each successive number is the sum of the previous number times 2, plus 1.
the sum of 1 plus 9 is 10 because 1+9
(xn+2-1)/(x2-1)
0
The sum is: 8
3x2 + 2x + 3 + x2 + x + 1 = 4x 2+ 3x + 4
The sum is 1511.