Coding Solutions

The factorial function (symbol: !) says to multiply all whole numbers from our chosen number down to 1.

Examples:

• 4! = 4 × 3 × 2 × 1 = 24
• 7! = 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5040
• 1! = 1

Wikipedia.

PHP: using gmp_fact function

A native PHP function called gmp_fact is available and it calculates the factorial of a number:

echo gmp_fact(5);

PHP: creating a recursive function

// Formula: n! = n*(n-1)*(n-2)*(n-3)...3.2.1 and zero factorial is defined as one i.e. 0! = 1.
function factorial($n)
{
    if ($n == 0)
        return 1;
    else
        return($n * factorial($n - 1));
}

echo factorial(5);

JAVA: simple for cycle

class Factorial {
    public static void main(String args[]){  
        int i,fact=1;
        int number=5;// It is the number to calculate factorial
        for(i=1; i<=number; i++) {
            fact=fact*i;
        }
        System.out.println("Factorial of "+number+" is: "+fact);    
    }
}

Javascript recursive function

var f = [];
function factorial (n) {
  if (n == 0 || n == 1)
    return 1;
  if (f[n] > 0)
    return f[n];
  return f[n] = factorial(n-1) * n;
}
console.log( factorial(4) ); // 24