#include <iostream>
using namespace std;

using NumberT = unsigned long long int;
//typedef int NumberT;
//typedef long NumberT;

NumberT Factorial(int n);

int main() {
   int i;

   for(i = 0 ; i < 22; i++) {
      cout << i << "! = " << Factorial(i) << endl;
   }

   return 0;
}

NumberT Factorial(int n) {
    NumberT result{1};
    int i;

    for(i = 2; i <= n; i++) {
       result *=i;
    }

    return result;
}