Answer to Question #58184 in C++ for M

Question

Let n = ak ak-1 ak-2. . .a1 a0 be an integer and t = a0 - a1 + a2 - …+ (-1)k ak. It is known that n is divisible by 11 if and only if t is divisible by 11. For example, suppose that n = 8784204. Then, t = 4 - 0 + 2 - 4 + 8 - 7 + 8 = 11. Because 11 is divisible by 11, it follows that 8784204 is divisible by 11. If n =54063297, then t = 7 - 9 + 2 - 3 + 6 - 0 + 4 - 5 = 2. Because 2 is not divisible by 11 then n is not divisible by 11.

Answer 1

#include <iostream>
#include <string>
using namespace std;
int main() {
long num;
cin >> num;
int sum = 0, coef = 1;
while (num>0) {
sum = sum + (num % 10) * coef;
coef *= -1;
num /= 10;
}
if (sum % 11 == 0)
cout << "Number is divisible by 11.";
else cout << "Number is not divisible by 11.";
return 0;
}