what does factorial mean code example

Example 1: Factorial

// METHOD ONE
const factorialNumber = num => {
    let factorials = []
    for(let i = 1; i <= num; i++) factorials.push(i)
    return factorials.reduce((acc , curr) => acc * curr, 1)
}

// METHOD TWO
const factorialNumber = num => {
    let factorial = 1, i = 1
    while(i <= num){ factorial *= i; i++ }
    return factorial
}
// METHOD THREE
function factorialNumber(num) {
    if(num < 1) return 1
    else return factorialNumber(num - 1) * num
}

Example 2: factorial of 8

function getFactorial($int)
{
   
    $factorial = 1;
    for ($i = $int; $i > 1; $i--)
    {
        $factorial *= $i;
    }
    echo "The factorial of " . $int . " is " . $factorial . '<br>';
}