Sum of given Number till one digit

To find sum of a given number till one digit we need a while loop and the count the sum till we get one digit number.

Ex - Like this num i have - 345678923 , sum of all these number(3+4+5+6+7+8+9+2+3 =47) is 47 so this is not one digit number then again while loop will run and we will get a new sum that(4+7=11) is 11, so again its not one digit so again sum(1+1 =2) now finally we got 2 that is one digit.

345678923 =  3+4+5+6+7+8+9+2+3 = 47 => 4+7 =11 => 1+1=2.
Thats it our program runs fine :)






public class SumNum {

    public static int getSum(long n){
        long remainder;
        int sum=0;
       
        while (n!=0){
            remainder = n%10;
            n=n/10;
            sum+=remainder;
        }
      
        return sum;
    }
    public static void main(String[] args) {

        Scanner scn=new Scanner(System.in);
        long num = scn.nextLong();
        int sum =getSum(num);
        while(sum>9){
            System.out.println(sum);
            sum = getSum(sum);
        }
        System.out.println(sum);
       
    }

}