leetcode-com-explore-challenge-card-july-leetcoding-challenge-547-week-4-july-22nd-july-28th-3402.cpp

class Solution {
public:
    int addDigits(int num) {
        
        while(num>=10){
            int sum=0;
            while(num>0){
                sum=sum+(num%10);
                num=num/10;
            }
            num =sum;
        }
        return num;
        
    }
};