For any positive number `n`, it’s factorial is given by:

factorial = 1*2*3...*n

Factorial of negative number cannot be found and factorial of 0 is 1.

## Program

```
#include <iostream>
using namespace std;
int main()
{
unsigned int n;
unsigned long long factorial = 1;
cout << "Enter a positive integer: ";
cin >> n;
for(int i = 1; i <=n; ++i)
{
factorial *= i;
}
cout << "Factorial of " << n << " = " << factorial;
return 0;
}
```

## Output

```
Enter a positive integer: 12
Factorial of 12 = 479001600
```