datagridview cell format

public class MyDgv : DataGridView
{
    protected override void OnEditingControlShowing(DataGridViewEditingControlShowingEventArgs e)
	{
		base.OnEditingControlShowing(e);

		// Set up handler for cells in column 0 only
		if (this.CurrentCell.ColumnIndex == 0)
		{
			// Remove handler before adding, to prevent accumulation of handlers
			e.Control.KeyPress -= new KeyPressEventHandler(MyDgv_OnKeyPress);
			e.Control.KeyPress += new KeyPressEventHandler(MyDgv_OnKeyPress);
		}
	}

	private void MyDgv_OnKeyPress(object sender, KeyPressEventArgs e)
	{
		if (e.KeyChar == 't')
		{
			// Multiply cell contents by 1000
			int val = int.Parse(((DataGridViewTextBoxEditingControl)sender).Text) * 1000;
			// Update cell
			((DataGridViewTextBoxEditingControl) sender).Text = val.ToString();
			// Prevent new character ('t') from being entered in the cell
			e.Handled = true;
		}
	}
} 

grd_dtls.Columns["grd_txt_qty"].DefaultCellStyle.Format = "N2";
             grd_dtls.Columns["grd_txt_qty"].ValueType = typeof(System.Double);

private void grd_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {