cument.getElementById('value');

        for (let i = 0; i< btn.length; i++) {
            btn[i].addEventListener('click', function(){
                if (this.innerHTML == '=') {
                    value.innerHTML = eval(value.innerHTML);
                } else {
                    if(this.innerHTML == 'Clear') {
                        value.innerHTML = "";
                    } else {
                        value.innerHTML += this.innerHTML;
                    }
                }
            })
    