# 1. Introduction

In this tutorial, we are going to learn how to write a Java program to find the sum of the digits of a number. This is a common programming exercise and can be used in various scenarios such as checking the divisibility of a number, forming new numbers, or in number theory problems.

# 2. Program Steps

1. Define a class named *SumOfDigits*.

2. Inside the *main* method, declare and initialize an integer variable *number* with the number whose digits you want to sum.

3. Create a variable *sum* initialized to 0, which will store the sum of the digits.

4. Use a *while* loop to iterate through each digit of the number, adding each digit to *sum* until the number becomes 0.

5. Print the *sum* variable which will be the sum of digits of the given number.

```
public class SumOfDigits { // Step 1: Define a class named SumOfDigits
public static void main(String[] args) { // Main method
// Step 2: Declare and initialize an integer variable number
int number = 12345;
// Step 3: Create a variable sum initialized to 0
int sum = 0;
// Step 4: Use a while loop to sum the digits
while (number != 0) {
sum += number % 10; // add the last digit to sum
number /= 10; // remove the last digit
}
// Step 5: Print the sum
System.out.println("Sum of digits: " + sum);
}
}
```

### Output:

Sum of digits: 15

# 4. Step By Step Explanation

– *Step 1:* A class named *SumOfDigits* is defined.

– *Step 2:* An integer variable *number* is declared and initialized with a value whose digits we want to sum.

– *Step 3:* A variable *sum* is initialized to 0, which will hold the sum of the digits.

– *Step 4:* A *while* loop is used to iterate through each digit of the number. In each iteration, the last digit is added to *sum*, and then removed by dividing the number by 10.

– *Step 5:* The program prints the value of *sum*, which represents the sum of the digits in the original number.