The digital root of an integer is the sum of its digits. If that sum is not a single digit number, the

process is repeated with the sum until a single digit is reached. For example, the digital root of 4726 is 4

+ 7 + 2 + 6 = 19 = 1 + 9 = 10 = 1 + 0 = 1. The iterative version is written as follows:

public static int digitalRoot(int num){

     int temp;

while (num > 9){

       temp = 0; 2

       while (num != 0){

         temp += num % 10;

num = num / 10;     // or num /= 10;

       }

num = temp;

     }

return num;

}

Take the above iterative method and make it recursive; then write a program to test your answer.

• Check values from 1 to 40000.

• Do not use a helper method.

Sample Runs:

Enter a positive integer: 4726

The digital root of 4726 is: 1

Enter a positive integer: 39

The digital root of 39 is: 3

Notes/Hints/Tips:

• The program must be recursive for full credit. 

• Get the non-recursive program to work first- then translate to recursion.