Mathematics14

Q14. Find the digital root  of a given number.
Digital Root: (also repeated digital sum) of a number is the (single digit) value obtained by an iterative process of summing digits, on each iteration using the result from the previous iteration to compute a digit sum. The process continues until a single-digit number is reached.

For example, the digital root of 65,536 is 7, because 6+5+5+3+6 = 25 and 2+5 = 7.

Answer:

public class Mathematics14 {
    public static int getDigitalRoot(int n) {
        if (n <= 0) {
            System.out.println("Digital root is not defined for negative numbers");
            return 0;
        }

        int digitalRoot = n % 9;
        if (digitalRoot == 0) {
            return 9;
        }
        return digitalRoot;
    }

    public static void main(String[] args) {
        System.out.println(getDigitalRoot(15));
        System.out.println(getDigitalRoot(181));
        System.out.println(getDigitalRoot(72));
        System.out.println(getDigitalRoot(65536));
    }
}