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Java Program for Sum the digits of a given number

  • Difficulty Level : Basic
  • Last Updated : 02 Nov, 2021

Given a number, find sum of its digits.
Example : 
 

Input : n = 687
Output : 21

Input : n = 12
Output : 3

1. Iterative: 
 

Java




// Java program to compute
// sum of digits in number.
import java.io.*;
 
class GFG {
     
    /* Function to get sum of digits */
    static int getSum(int n)
    {   
        int sum = 0;
         
        while (n != 0)
        {
            sum = sum + n % 10;
            n = n/10;
        }
     
    return sum;
    }
 
    // Driver program
    public static void main(String[] args)
    {
        int n = 687;
 
        System.out.println(getSum(n));
    }
}
 
// This code is contributed by Gitanjali

Time Complexity: O(|n|)

Auxiliary Space: O(1)

How to compute in single line? 
 

Java




// Java program to compute
// sum of digits in number.
import java.io.*;
 
class GFG {
     
    /* Function to get sum of digits */
    static int getSum(int n)
    {
        int sum;
 
        /* Single line that calculates sum */
        for (sum = 0; n > 0; sum += n % 10,
                                  n /= 10);
 
        return sum;
    }
 
    // Driver code
    public static void main(String[] args)
    {
        int n = 687;
 
        System.out.println(getSum(n));
    }
}
 
// This code is contributed by Gitanjali

Time Complexity: O(|n|)

Auxiliary Space: O(1)

2. Recursive 
 

Java




// Java program to compute
// sum of digits in number.
import java.io.*;
 
class GFG {
   
    /* Function to get sum of digits */
    static int sumDigits(int no)
    {
        return no == 0 ? 0 : no%10 +
                  sumDigits(no/10) ;
    }
 
    // Driver code
    public static void main(String[] args)
    {
    int n = 687;
 
    System.out.println(sumDigits(n));
    }
}
 
// This code is contributed by Gitanjali

Time Complexity: O(log10n)

Auxiliary Space: O(log10n)

Please refer complete article on Program for Sum the digits of a given number for more details!
 


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