Check if a large number is divisible by 75 or not in C++

Here we will see how to check a number is divisible by 75 or not. In this case the number is very large number. So we put the number as string.

A number will be divisible by 75, when the number is divisible by 3 and also divisible by 25. if the sum of digits is divisible by 3, then the number is divisible by 3, and if last two digits are divisible by 25, then the number is divisible by 25.

Example

Live Demo

#include <bits/stdc++.h>
using namespace std;
bool isDiv75(string num){
   int n = num.length();
   long sum = accumulate(begin(num), end(num), 0) - '0' * n;
   if(sum % 3 != 0)
      return false;
      int last_two_digit_val = (num[n-2] - '0') * 10 + ((num[n-1] - '0'));
   if(last_two_digit_val % 25 == 0)
      return true;
      return false;
}
int main() {
   string num = "1754586672150";
   if(isDiv75(num)){
      cout << "Divisible";
   }else{
      cout << "Not Divisible";
   }
}