Help using factorial function...

I'm doing a little bit of homework, and one of my problems is as follows:

Write a function that will return N! when N is passed to it.

Your program should ask for N and K. The probability of K numbers being selected from N numbers is:

Code:

N!

Probability = --------

K!(N-K)!

Basically, it's a lottery program, where the user enters the number of chances he's purchases, and enters the number of chances total. The program computes the probability. I know that my factorial function that I created is not the problem, it has to be somewhere in the code itself. Any help is appreciated, here's the code:

Code:

`#include <iostream>`

using namespace std;

int fac(int n);

int main()

{

int fact1, fact2, picks, total, fact3, subtraction;

float output;

cout << "Enter the amount of chances you are choosing..." << '\n' << endl;

cin >> picks;

cout << '\n' << "Now, enter the total number of choices..." << '\n' << endl;

cin >> total;

subtraction = total - picks;

output = fac(total) / (fac(total * fac(subtraction)));

cout << '\n' << "Your chances are 1 in " << output << "." << endl;

return (0);

}

int fac(int n)

{

int i=0, fact=1;

for(i=1;i<=n;++i)

{

fact=fact*i;

}

return(fact);

}

Thanks!