Even number's sum from an integer

Question

How to get the even number' sum from an integer input.

var intInput = 10;

Now i want the even' sum. In this case = 2+4+6+8+10 = 30

var evenCount = 0;
if (i % 2==0) 
{
    evenCount = evenCount + i;
}

How to achieve this?

Answer 1

var evenCount = (intInput / 2) * (intInput / 2 + 1);

This is just twice the sum of all the integers from zero to half the specified number.

2+4+6+8+10 = 2 (1+2+3+4+5)

Answer 2

How about this?

var sum = Enumerable.Range(1,10).Where(x=> x%2==0).Sum();

Answer 3

int intInput=10;
var evenCount = 0;
for (int i=1;i<=intInput;i++)
{
 if (i % 2==0) 
    {
        evenCount = evenCount + i;
    }
}

Answer 4

Try

   var intInput =10;
   var evenValueSum = 0;
 for(int i=intInput ;i>0;i--)
{
     if(i %2 ==0)
{
     evenValueSum += i;
}
}

Answer 5

int end = inputNum / 2;
int sum = 0;
for(int i = 1; i <= end; i++)
    sum += i * 2;

Answer 6

int evenCount = 0;
int countFrom = 1;
int countTo = 10;
for (int i = countFrom; i <= countTo; i++) {
    if (i % 2 == 0) {
        evenCount += i
    }
}