calc.js

function calculator(x, y) {
    function add() {
        return x + y;
    }
    
    function subtract() {
        return x - y;
    }
    
    function multiply() {
        return x * y;
    }

    return {
        add: add,
        subtract: subtract,
        multiply: multiply
    }
} 

const calc = calculator(10, 5);
console.log(calc.add()); // 15
console.log(calc.subtract()); // 5
console.log(calc.multiply()); // 50