C program to find sum of digits of a five digit number

In C programming, finding the sum of digits of a five-digit number involves extracting each digit and adding them together. We use the modulo operator (%) to extract the last digit and integer division (/) to remove it from the number.

Syntax

int digitSum = 0;
while (number != 0) {
    digitSum += number % 10;
    number /= 10;
}

So, if the input is like num = 58612, then the output will be 22 because 5 + 8 + 6 + 1 + 2 = 22.

Algorithm

To solve this, we follow these steps −

• Initialize sum to 0
• While the number is not equal to 0:
  • Extract the last digit using modulo operator (num % 10)
  • Add this digit to sum
  • Remove the last digit by dividing by 10 (num / 10)
• Return the sum

Example

Let us see the following implementation to get better understanding −

#include <stdio.h>

int main() {
    int num = 58612;
    int sum = 0;
    int originalNum = num;
    
    while (num != 0) {
        sum += num % 10;
        num = num / 10;
    }
    
    printf("Number: %d<br>", originalNum);
    printf("Sum of digits: %d<br>", sum);
    return 0;
}

Number: 58612
Sum of digits: 22

How It Works

The algorithm works by repeatedly extracting the rightmost digit:

• Iteration 1: 58612 % 10 = 2, sum = 2, num = 5861
• Iteration 2: 5861 % 10 = 1, sum = 3, num = 586
• Iteration 3: 586 % 10 = 6, sum = 9, num = 58
• Iteration 4: 58 % 10 = 8, sum = 17, num = 5
• Iteration 5: 5 % 10 = 5, sum = 22, num = 0

Conclusion

This method efficiently calculates the sum of digits using modulo and division operations. The algorithm works for any positive integer, not just five-digit numbers, making it a versatile solution.