Digital Root (repeated digital sum) of the given large integer in C++ Program

In this tutorial, we are going to learn how to find the digital root of a given number.

The digital root is the sum of a number of digits (until the sum of the digits becomes a single digit).

We are given an integer in string format. And we have to find the sum of the digits repeatedly until the sum becomes a single digit.

Let's see the steps to solve the problem.

Initialize an integer in the string format.
Iterate through the number and add each digit to the sum variable.
If the sum is 0, then print 0.
Else if the sum is divisible by 9, then the answer is 9.
Else the answer is sum modulo 9.

Example

Let's see the code.

Live Demo

#include<bits/stdc++.h>
using namespace std;
int digitalRoot(string n) {
   int digitsSum = 0;
   for (int i = 0; i < n.length(); i++) {
      digitsSum += n[i] - '0';
   }
   if (digitsSum == 0) {
      return 0;
   }
   return digitsSum % 9 == 0 ? 9 : digitsSum % 9;
}
int main() {
   string n = "12345";
   cout << digitalRoot(n) << endl;
   return 0;
}

Output

If you run the above code, then you will get the following result.

Conclusion

If you have any queries in the tutorial, mention them in the comment section.

Hafeezul Kareem

Published on 27-Jan-2021 12:39:47

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