C Program To Find Sum of All Even Numbers From 1 To N, using While loop

Lets write a C program to find sum of all the even numbers from 1 to N, using while loop.

Even Number: An even number is an integer that is exactly divisible by 2.

For Example: 8 % 2 == 0. When we divide 8 by 2, it give a reminder of 0. So number 8 is an even number.

If user enters num = 5. Even numbers between 1 to 5 are 2, 4. So we add 2 and 4. i.e., 2 + 4 = 6. We display 6 to the console window as result.

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Video Tutorial: C Program To Find Sum of All Even Numbers From 1 To N, using While loop

Logic To Find Sum of All Even Numbers From 1 To N, using While loop

Since we are checking for even numbers from 1 to user entered number, we assign value of variable count to 1. While loop keeps iterating until value of count is less than or equal to value of user input number. For each iteration of while loop we increment the value of count by 1.

Inside while loop we check for the condition, count%2 == 0. If it’s true, then we add the value present inside variable count to previous value present in variable sum.

After the control exits while loop we display the value present in variable sum – which has the sum of all the even numbers from 1 to user entered number.

Source Code: C Program To Find Sum of All Even Numbers From 1 To N, using While loop

#include<stdio.h>

int main()
{
    int num, count = 1, sum = 0;

    printf("Enter the limit\n");
    scanf("%d", &num);

    while(count <= num)
    {
        if(count%2 == 0)
        {
            sum = sum + count;
        }
        count++;
    }
    printf("Sum of Even numbers from 1 to %d is %d\n", num, sum);
    return 0;
}

Output 1:
Enter the limit
5
Sum of Even numbers from 1 to 5 is 6

Output 2:
Enter the limit
20
Sum of Even numbers from 1 to 20 is 110

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