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+/**%0A * Problem: https://leetcode.com/problems/add-digits/%0A * Recursively call this method until the num is smaller than 10.%0A **/%0Apublic class Solution %7B%0A    public int addDigits(int num) %7B%0A        if(num %3C 10) return num;%0A        int sum = 0;%0A        while(num %3E 0) %7B%0A            sum += num %25 10;%0A            num /= 10;%0A        %7D%0A        return addDigits(sum);%0A    %7D%0A%7D%0A

Create Add_Digits.java