let array = [2, 4, 1, 2, 3, 4, 5, 6, 7];
let factors = [];
let final = [];
let total = 0;

function getFactors() {
  array.forEach((number) => {
    let i = array.indexOf(number);
    let factor[i] = array[i] + 1;
  });
};

getFactors().then(function{
  array.forEach((number) => {
  let i = array.indexOf(number);
  final[i] = array[i] * factor[i];
});

function check() {
  final.forEach((number) => {
    let i = array.indexOf(number);
    total = total + final[i];

    if (total/11 % != 0) return console.log("Error.");
    console.log("Check successfully completed.");
  });
}

check();
// by fred