C Program to calculate sum of Even numbers till N

Description

Get input n and calculate the sum of even numbers till n
Input:
5
Output:
6(2+4)

Solution

#include<stdio.h>
int main()
{
	int n,i,sum=0;
	printf("Enter a number:");
	scanf("%d",&n);
	for(i=0;i<=n;i=i+2)
	{
		sum=sum+i;
	}
	printf("The sum of even numbers till %d is : %d",n,sum);
	return 0;
}

Explanation

Instruction(s) inside the for block{} are executed repeatedly till  the second expression (i<=n) is true.

Here i is initialized to 2 and incremented by 2 for each iteration, instructions inside the for block are executed unless i becomes greater than n. so value of i (2,4,6,...n)will be added to sum.

after adding all n even numbers to sum, sum will be printed using printf statement.



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