Java Program to find sum of digits of a number

Java Program to Find Sum of Digits of a Number

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In the previous article, we have seen Java Program to generate a sequence of random numbers

In this article we are going to see how to find sum of digits of a number using Java programming language.

Java Program to Find Sum of Digits of a Number

As we know dividing any number by 10, the remainder always gives the unit place digit. The number will be reduced to zero after we exhausted all its digits. We will use this theory to get our output.

Example:

528= 5+2+8 = 15
3491= 3+4+9+1= 17
12= 1+2= 3
80451= 8+0+4+5+1 = 18

Let’s see different ways to find sum of digits of a number.

Method-1: Java Program to Find Sum of Digits of a Number By Using Modulo Operator and Number is Integer Value

Approach:

  1. Create Scanner class object.
  2. Ask user to enter the number.
  3. Declare a variable sum = 0 to store the sum of the digits.
  4. Use the modulo operator to obtain the unit place digit and add it to sum.

Program:

import java.util.Scanner;

public class Main
{
    public static void main(String[] args) 
    {
        // creating scanner class object
        Scanner sc = new Scanner(System.in);
        // taking input from user
        System.out.print("Enter a number: ");
        int n = sc.nextInt();
        // calling method to find sum of digits
        int sum = findSum(n);
        // printing sum of digits
        System.out.println("Sum of each digit of the number: " + sum);
    }

    //user defined method
    //to find sum of each digits of a number
    private static int findSum(int n) 
    {
        // variable to store sum
        int sum = 0;
        while (n > 0) {
            // extracting last digit and adding to sum
            sum += n % 10;
            n /= 10;
        }
        return sum;
    }
}


Output:

Enter a number: 3476
Sum of each digit of the number: 20

Method-2: Java Program to Find Sum of Digits of a Number By Using Modulo Operator and Number is Numeric String Value

Approach:

  1. Use the Integer.parseInt() method to covert the numeric string into an integer.
  2. Declare a variable sum=0 to store the sum of the digits.
  3. Use the modulo operator to obtain the unit place digit and add it to sum.

Program:

public class Main
{
    public static void main(String[] args) 
    {
        String num = "12345";
        
        //calling method to find sum of digits
        int sum = findSum(num);
        //printing sum of digits
        System.out.println("Sum of each digit of the number: " + sum);
    }
    
    //user defined method
    private static int findSum(String num) 
    {
        //convert numeric string into int type
        int n = Integer.parseInt(num);
        //variable to store sum
        int sum = 0;
        while (n > 0) 
        {
            //extracting last digit and adding to sum
            sum += n % 10;
            n /= 10;
        }
        return sum;
    }
}


Output:

Sum of each digit of the number: 15

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