text: function solve() {
    let arr = JSON.parse(document.getElementById('arr').value);
    let result = document.getElementById('result');
  
    for (let i = 0; i < arr.length; i++){
        let prod = +arr[i] * arr.length;
        let p = document.createElement('p');
        p.innerHTML = `${i} -> ${prod}`;
        result.appendChild(p);
    }
  }