Check if a large number is divisible by 2, 3 and 5 or not in C++

Here we will see how to check a number is divisible by 2, 3 and 5 or not. In this case the number is very large number. So we put the number as string.

A number will be divisible by 2, 3 and 5 if that number is divisible by LCM of 2,3 and 5. So the LCM of 2, 3, 5 is 30. We have to check the number is divisible by 30 or not. A number is divisible by 30 when it is divisible by 10 (last digit is 0) and divisible by 3 (sum of all digits is divisible by 3)

Example

 Live Demo

#include <bits/stdc++.h> using namespace std; bool isDiv30(string num){    int n = num.length();    if(num[n - 1] != '0')       return false;       long sum = accumulate(begin(num), end(num), 0) - '0' * n;    if(sum % 3 == 0)       return true;    return false; } int main() {    string num = "353730746028908374890";    if(isDiv30(num)){       cout << "Divisible";    } else {       cout << "Not Divisible";    } }

Output

Divisible