# PHP Program - Find Factorial of a Number

The factorial of a positive integer is the multiplication of all positive integer less than or equal to that number.

$factorial$ $of$ $number$ $n$ = $n! = n(n-1)(n-2)...1$

### For Example:

$5! = 5\times4\times3\times2\times1 = 120$

$4! = 4\times3\times2\times1 = 24$

### Example: Using Recursive method

In the below example, a recursive function called factorial() is used to calculate factorial of a number.

#include <iostream>
using namespace std;

static int factorial(int);

static int factorial(int x) {
if (x == 0 || x == 1)
{return 1;}
else
{return x*factorial(x-1);}
}

int main(){
cout<<"10! =  "<<factorial(10)<<"\n";
cout<<"6! =  "<<factorial(6)<<"\n";
return 0;
}


Output

10! =  3628800
6! =  720


### Example: Using Iterative method

The factorial of a number can also be calculated using iterative method.

#include <iostream>
using namespace std;

static int factorial(int);

static int factorial(int x) {
int finalnum = 1;
for(int i = x; i > 0; i--)
{
finalnum = finalnum * i;
}
return finalnum;
}

int main(){
cout<<"10! =  "<<factorial(10)<<"\n";
cout<<"6! =  "<<factorial(6)<<"\n";
return 0;
}


Output

10! =  3628800
6! =  720


### Example: Using Ternary Operator

In the below example, the factorial of a number is calculated using ternary operator.

#include <iostream>
using namespace std;

static int factorial(int);

static int factorial(int x) {
int y = (x == 0 || x == 1)? 1 : x*factorial(x-1);
return y;
}

int main(){
cout<<"10! =  "<<factorial(10)<<"\n";
cout<<"6! =  "<<factorial(6)<<"\n";
return 0;
}


Output

10! =  3628800
6! =  720