#### Digital Root

S
```/** Author : Suraj Kumar Modi
* https://github.com/skmodi649
*/
/** You are given a number n. You need to find the digital root of n.
* DigitalRoot of a number is the recursive sum of its digits until we get a single digit number.
*
* Test Case 1:
* Input:
* n = 1
* Output:  1
* Explanation: Digital root of 1 is 1
*
* Test Case 2:
* Input:
* n = 99999
* Output: 9
* Explanation: Sum of digits of 99999 is 45
* which is not a single digit number, hence
* sum of digit of 45 is 9 which is a single
* digit number.
*/
/** Algorithm :
* Step 1 : Define a method digitalRoot(int n)
* Step 2 : Define another method single(int n)
* Step 3 : digitalRoot(int n) method takes output of single(int n) as input
* if(single(int n) <= 9)
* return single(n)
* else
* return digitalRoot(single(n))
* Step 4 : single(int n) calculates the sum of digits of number n recursively
* if(n<=9)
* return n;
* else
* return (n%10) + (n/10)
* Step 5 : In main method simply take n as input and then call digitalRoot(int n) function and print the result
*/
package com.thealgorithms.maths;

import java.util.*;

class DigitalRoot {

public static int digitalRoot(int n) {
if (single(n) <= 9) // If n is already single digit than simply call single method and return the value
{
return single(n);
} else {
return digitalRoot(single(n));
}
}

// This function is used for finding the sum of digits of number
public static int single(int n) {
if (n <= 9) // if n becomes less than 10 than return n
{
return n;
} else {
return (n % 10) + single(n / 10);                     // n % 10 for extracting digits one by one
}
}                                                             // n / 10 is the number obtainded after removing the digit one by one
// Sum of digits is stored in the Stack memory and then finally returned

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number : ");
int n = sc.nextInt();                                     // Taking a number as input from the user
System.out.println("Digital Root : " + digitalRoot(n));     // Printing the value returned by digitalRoot() method
}
}

/**
* Time Complexity : O((Number of Digits)^2) Auxiliary Space Complexity :
* O(Number of Digits) Constraints : 1 <= n <= 10^7
*/
```  