10. Factorial Division

function solve (firstNum, secondNum) {

    function calculateFactorial() {
        let num1 = 1;
        let num2 = 1;
        for (let i = firstNum; i > 0; i--) {
            num1 *= i;
        }
        for (let i = secondNum; i > 0; i--) {
            num2 *= i;
        }
        return `${(num1 / num2).toFixed(2)}`;
    }
    console.log(calculateFactorial());
}

Решение с рекурсия:

function solve (firstNum, secondNum) {

    function factorial(num) {
        if (num === 0) {
            return 1;
        } else {
            return (num * factorial(num - 1));
        }
    }
    console.log(`${(factorial(firstNum) / factorial(secondNum)).toFixed(2)}`);
}

Или:

function solve (firstNum, secondNum) {

    function factorial(num) {
        return (num < 2) ? 1 : factorial(num - 1) * num;
    }
    console.log(`${(factorial(firstNum) / factorial(secondNum)).toFixed(2)}`);
}