Check if a large number is divisible by 11 or not in C++

Here we will see how to check a number is divisible by 11 or not. In this case the number is very large number. So we put the number as string.

To check whether a number is divisible by 11, if the sum of odd position values and the sum of even position values are same, then the number is divisible by 11.

Example

#include <bits/stdc++.h>
using namespace std;
bool isDiv11(string num){
   int n = num.length();
   long odd_sum = 0, even_sum = 0;
   for(int i = 0; i < n; i++){
      if(i % 2 == 0){
         odd_sum += num[i] - '0';
      } else {
         even_sum += num[i] - '0';
      }
   }
   if(odd_sum == even_sum)
      return true;
      return false;
}
int main() {
   string num = "1234567589333892";
   if(isDiv11(num)){
      cout << "Divisible";
   } else {
      cout << "Not Divisible";
   }
}

Output

Divisible