Check if a large number is divisible by 3 or not in C++

Here we will see how to check a number is divisible by 3 or not. In this case the number is very large number. So we put the number as string.

A number will be divisible by 3, if the sum of digits is divisible by 3.

Example

Live Demo

#include <bits/stdc++.h> using namespace std; bool isDiv3(string num){    int n = num.length();    long sum = accumulate(begin(num), end(num), 0) - '0' * n;    if(sum % 3 == 0)       return true;       return false; } int main() {    string num = "3635883959606670431112222";    if(isDiv3(num)){       cout << "Divisible";    } else {       cout << "Not Divisible";    } }

Output

Divisible