C Exercises: Find the Deficient numbers (integers) between 1 to 100

Last update on August 05 2025 12:55:04 (UTC/GMT +8 hours)

5. Deficient Numbers Between 1 and 100 Variants

Write a program in C to find the Deficient numbers (integers) between 1 to 100.

Sample Solution:

C Code:

#include <stdio.h>
#include <stdbool.h>
#include <math.h>

// Function to calculate the sum of divisors of a number
int getSum(int n)
{
    int sum = 0;
    for (int i = 1; i <= sqrt(n); i++) // Loop through numbers from 1 to the square root of 'n'
    {
        if (n % i == 0) // Check if 'i' is a divisor of 'n'
        {
            if (n / i == i)
                sum = sum + i; // If 'i' is a divisor and is equal to the square root of 'n', add it to 'sum'
            else
            {
                sum = sum + i; // Add 'i' to 'sum'
                sum = sum + (n / i); // Add 'n / i' to 'sum'
            }
        }
    }
    sum = sum - n; // Subtract the number 'n' from the sum of its divisors
    return sum; // Return the sum of divisors
}

// Function to check if a number is a deficient number
bool checkDeficient(int n)
{
    return (getSum(n) < n); // Return true if the sum of divisors is less than 'n', otherwise return false
}

// Main function
int main()
{
    int n, ctr = 0; // Declare variables 'n' for the number, 'ctr' to count deficient numbers
    printf("\n\n The Deficient numbers between 1 to 100 are: \n");
    printf(" ------------------------------------------------\n");

    for (int j = 1; j <= 100; j++) // Loop through numbers from 1 to 100
    {
        n = j; // Assign the current value of 'j' to 'n'
        if (checkDeficient(n) == true) // Check if 'n' is a deficient number
        {
            printf("%d ", n); // Print the deficient number
            ctr++; // Increment the counter for deficient numbers
        }
    }

    printf("\n The Total number of Deficient numbers are: %d \n", ctr); // Print the total count of deficient numbers

    return 0;
}

Sample Output:

The Deficient numbers between 1 to 100 are:                                                                  
 ------------------------------------------------                                                             
1 2 3 4 5 7 8 9 10 11 13 14 15 16 17 19 21 22 23 25 26 27...

Visual Presentation:

C programming: Find the Deficient numbers (integers) between 1 to 100.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to list all deficient numbers within a user-specified range.
Write a C program to count the number of deficient numbers in a given interval.
Write a C program to display each deficient number along with its proper divisor sum.
Write a C program to find deficient numbers that are also prime numbers.

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