Program to find out sum of digits

🔢 Find the Sum of Digits of a Number (Java)

🧩 What problem are we solving?

We often need to find the sum of digits in a number — for example, to check whether a number is divisible by 3 or 9, or as a simple exercise in integer manipulation.

Given a number (like 111), the goal is to extract each digit, add them together, and display the total.
For 111, the result is 1 + 1 + 1 = 3.

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⚙️ How it works (step by step)

1. Start with a number, say a = 111.

2. Initialize sum = 0.

3. Repeat while a > 0:

   • Get the last digit using the modulo operator: d = a % 10

   • Add it to sum: sum = sum + d

   • Remove the last digit from the number using integer division: a = a / 10

4. When a becomes 0, print the sum.

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🧠 Example Walkthrough

Let’s trace the steps for a = 111:

Step	a	a % 10 (digit)	sum after addition	a / 10 (next a)
1	111	1	1	11
2	11	1	2	1
3	1	1	3	0

✅ Final sum = 3

Main program

package com.vinod.test;


/**
 *@authorvinodkariyathungalkumaran
 *
 */
public class FindSumOfDigits {
    public static void main(String[] args) {
        {
            int sum, d;
            int a = 111;
            sum = 0;
            for (int i = 1; i <= 10; i++) {
                d = a % 10;
                a = a / 10;
                sum = sum + d;
            }
            System.out.println("Sum of Digit =" + sum);
        }
    }

}

Ouput

Sum of Digit =3