C Exercises: Calculate the sum of the series 1 +11 + 111 + 1111 + .. n terms

C For Loop: Exercise-26 with Solution

Write a program in C to find the sum of the series 1 +11 + 111 + 1111 + .. n terms.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h> // Include the standard input/output header file.

int main() {
    int n, i;  // Declare variables for loop control and input.
    long sum = 0; // Initialize a variable to hold the sum of the series.
    long int t = 1; // Initialize a variable to generate the series.

    printf("Input the number of terms : "); // Prompt the user for input.
    scanf("%d", &n); // Read the value of 'n' from the user.

    for(i = 1; i <= n; i++) // Loop to generate and sum the series.
    {
        printf("%ld  ", t); // Print the current term of the series.

        if (i < n)
        {
            printf("+ "); // Print addition sign between terms (except the last term).
        }

        sum = sum + t; // Add the current term to the running sum.
        t = (t * 10) + 1; // Generate the next term of the series.
    }

    printf("\nThe Sum is : %ld\n", sum); // Print the final sum of the series.

    return 0; // Return 0 to indicate successful execution.
}

Sample Output:

Input the number of terms : 5                                                                                 
1 + 11 + 111 + 1111 + 11111                                                                                  
The Sum is : 12345 

Flowchart:

C Programming Code Editor:

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