function FormatTextBox(id) {
  var txtBox = $(id).val();
  //strip bracket to get the number only
  txtBox = txtBox.replace("[","").replace("]","");
  var val = parseFloat(txtBox);

  if (val < 0) {
    txtBox.val("[" + val + "]");
  } else {
    txtBox.val(val);
  }
  return val;
}