function calculate(array) {
    var sum = 0;
    for (var i = 0; i < array.length; i++) {
        sum = sum + array[i];
    }
    return sum;
}
document.write(calculate([24, 88, 12, 4]));

function calculate(array) {
  var sum = 0;
  var count = array.length;
  for (var i = 0; i < count; i++) {
    sum = sum + array[i];
  }
  return sum / count;
}

return sum / array.lenght;

document.write(calculate([24, 88, 12, 4]));

document.write(calculate({24, 88, 12, 4}));