# C++ : Find Factorial of a Number

Tutorial by:Manisha Dubey      Date: 2016-06-18 04:16:00

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.

In this program below, user is asked to enter a positive integer. Then the factorial of that number is computed and displayed in the screen.

## Source Code

``````#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```

Here variable factorial is of type `unsigned long long`. It is because factorial of a number is always positive, that's why `unsigned` qualifier is added to it. Since the factorial a number can be large, it is defined as `long long`.

## C++

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