Sum of Digits of a Number in Java Example

In this program, we first input the number (Say num = 12345). Next the control reaches the while loop where it checks the condition (num>0) which is true as (12345>0) so the body of the loop is executed.

On First pass,       x=5       Sum=0+5=5            num = 1234

On Second pass,  x=4        Sum=5+4= 9          num = 123

On Third pass,     x=3       Sum=9+3=12           num = 12

On Fourth pass,   x=2       Sum=12+2=14         num = 1

On Fifth pass,      x=1        Sum=14+1=15         num = 0

Finally, when the condition becomes false, the control reaches out of the loop and finally displays the sum of digits of a number. In this program, the number of times the loop will be executed is unknown in advance.

//program to Find Sum of Digits of a Number 
 import java.util.Scanner; //program uses Scanner class 
 public class SumDigits 
 { 
     public static void main(String[] args) 
     { 
        long num,x,sum=0; 
        Scanner input=new Scanner(System.in); 
        System.out.println("Enter Number :"); 
        num=input.nextInt(); 
              while(num>0) 
           { 
                  x = num%10; 
                  sum += x; 
                  num /=10; 
            } 
                  System.out.println("Sum of Digits of Number is :" +sum); 
       }           
  }