how to sum all td values ?

Code:

<td><?php echo $row['remun'];?></td>
 <td><?php echo $row['lum'];?></td>

Code:

for example
Ist column   2nd column
100              150
200              150
300              150

Code:

<input type="text"  name="grand_total" id="grand_total" />

Code:

<script>    
 $('#dynamic-table tr').each(function() {
  if (!this.rowIndex) return; // skip first row
  var customerId = this.cells[4].innerHTML;
  alert(customerId);
 $("#grand_total").val(customerId);
});

i get only first row value but i want sum of all fields.