C Exercises: Find out the sum of an A.P. series

Last update on March 18 2025 13:34:31 (UTC/GMT +8 hours)

49. Sum of A.P. Series

Write a C program to find the sum of an A.P. series.

An Arithmetic Progression (A.P.) series is a sequence of numbers where the difference between any two consecutive terms is constant. It follows a specific pattern where each term is obtained by adding a fixed number to the previous term. For example, in the series 2, 5, 8, 11, 14, each term increases by 3, indicating a common difference of 3.

In this program, you find the sum of an Arithmetic Progression (A.P.) series:

Input the first term (a), the common difference (d), and the number of terms (n).
Apply the formula for the sum of an A.P.: sum = (n/2) [2a + (n - 1) d].
Output the computed sum.

Visual Presentation:

Sample Solution:

C Code:

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

void main(){

    int n1, df, n2, i, ln; // Declare variables to store input and results.
    int s1 = 0; // Initialize the sum of the arithmetic progression.

    printf("\n\nFind out the sum of A.P. series :\n "); // Print a message.
    printf("----------------------------------------\n"); // Print a separator.

    printf("Input  the starting number of the A.P. series: "); // Prompt the user for the starting number.
    scanf("%d", &n1); // Read the starting number.

    printf("Input the number of items for the A.P. series: "); // Prompt the user for the number of items in the series.
    scanf("%d", &n2); // Read the number of items.

    printf("Input the common difference of A.P. series: "); // Prompt the user for the common difference.
    scanf("%d", &df); // Read the common difference.

    // Calculate the sum of the arithmetic progression.
    s1 = (n2 * (2 * n1 + (n2 - 1) * df)) / 2;
    ln = n1 + (n2 - 1) * df; // Calculate the last term of the series.

    printf("\nThe Sum of the A.P. series are : \n"); // Print a message.

    // Loop to print the terms of the arithmetic progression.
    for (i = n1; i <= ln; i = i + df) {
         if (i != ln)
             printf("%d + ", i); // Print the term and a plus sign.
         else
             printf("%d = %d \n\n", i, s1); // Print the last term and the total sum.
    }
}

Output:

Find out the sum of A.P. series :                                                                           
 ----------------------------------------                                                                     
Input  the starting number of the A.P. series: 1                                                              
Input the number of items for  the A.P. series: 10                                                            
Input  the common difference of A.P. series: 4                                                                
                                                                                                              
The Sum of the  A.P. series are :                                                                             
1 + 5 + 9 + 13 + 17 + 21 + 25 + 29 + 33 + 37 = 190

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to calculate the sum of an arithmetic progression using the formula and then display the series.
Write a C program to compute the sum of an A.P. series and determine the average of its terms.
Write a C program to generate the terms of an A.P. series recursively and compute their sum.
Write a C program to calculate the sum of an A.P. series with error checking for a zero common difference.

C Programming Code Editor:

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