get total value from a datagridview

private decimal[] d;
d = new decimal[31];

for(int count = 0; count < myVariable; count++)
{
     d[count] = Convert.ToDecimal(myGrid.Rows[e.RowIndex].Cells[count].Value);
}

myGrid.Rows[e.RowIndex].Cells.Value = d[0] + d[29]; //for example.

I added this in CellEndEdit event.

decimal total = 0M;
foreach(DataGridViewRow row in datagridview1.Rows)
{
      decimal temp = 0M;
      if(Decimal.TryParse(dataGridView[0, row.Index].Value.ToString(), out temp)) // 0 is 1st column - set your column index!
           total += temp;
}
//set result of total in last row:
datagridview1[0, datagridview1.Rows.Count -1].Value = total.ToString();