C# Program to Find Sum of Digits of a Number Using Recursion

Given a number, we need to find the sum of digits in the number using recursion. In C#, recursion is a process in which a function calls itself directly or indirectly and the corresponding function is known as a recursive function. It is used to solve problems easily like in this article using recursion we will find the sum of digits of a number.

Example

Input: 456
Output: 15

Input: 123
Output: 6

Approach:

To find the sum of digits of a number using recursion follow the following approach:

• We call the SumOfDigits function with the argument n.
• In function, the last digit is retrieved by n % 10.
• The function is recursively called with argument as n / 10.[i.e. n % 10 + SumOfDigit(n / 10)]
• The function is called recursively until the n > 0.

Example 1:

C#

// C# program to find the sum of digits of a number
// using recursion
using System;

class GFG{

// Method to check sum of digit using recursion
static int SumOfDigit(int n)
{

    // If the n value is zero then we
    // return sum as 0.
    if (n == 0)
        return 0;

    // Last digit + recursively calling n/10
    return(n % 10 + SumOfDigit(n / 10));
}

// Driver code
public static void Main()
{
    int n = 123;
    int ans = SumOfDigit(n);

    Console.Write("Sum = " + ans);
}
}

Output

Sum = 6

Example 2:

C#

// C# program to find the sum of digits of a number
// using recursion
// Here, we take input from user
using System;

class GFG{

// Method to check sum of digit using recursion
static int SumOfDigit(int n)
{

    // If the n value is zero then we return sum as 0.
    if (n == 0)
        return 0;

    // Last digit + recursively calling n/10
    return (n % 10 + SumOfDigit(n / 10));
}

// Driver code
public static void Main()
{
    int number, res;

    // Taking input from user
    Console.WriteLine("Hi! Enter the Number: ");
    number = int.Parse(Console.ReadLine());
    res = SumOfDigit(number);

    // Displaying the output
    Console.WriteLine("Sum of Digits is {0}", res);
    Console.ReadLine();
}
}

Output:

Hi! Enter the Number:
12345
The Sum of Digits is 15