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In this tutorial, we will be learning to write Java Program to print or calculate the sum of digits of a given number using a while loop. This program prints the sum of the digits of a number.

For Example:

Suppose the number is 12345,

Output should be (1+2+3+4+5) 15

Steps of program to calculate sum of input digit

1. Here we are using “Scanner” to take input for numbers.
2. We run a while loop till the number in check is not zero.
3. Inside the loop, we are adding individual digits.

Suppose Given number = 12, sum=0
       since 12>0 so it will go inside while loop
       to get the last digit of the number we are using the the modulo remainder property .i.e., 12%10 = 2
       now, sum = 0+2 
       and the number is changed to 12/10 = 1.

This will comtinue till the number < 0

Java Program to find the sum of digits of a given number

import java.util.*;
public class Main
{
	public static void main(String args[])
	{
		Scanner sc = new Scanner(System.in);				
		int remainder,sum = 0;		
		System.out.println("Enter the Number to find Sum: ");
		int number = sc.nextInt();		
		while(number>0) {			
			remainder = number%10;
			sum=sum+remainder;
			number = number/10;
		}
		System.out.println("Sum of the digits for the number is : " +sum+".");
		sc.close();
	} 
}

Output 1

Enter the Number to find Sum: 
3421
Sum of the digits for the number is : 10.

Output 2

Enter the Number to find Sum: 
54671
Sum of the digits for the number is : 23.