How To Refresh A Computed Column In DataGridView Before Leaving The cell ?

Hi all,

I'm using a DataTable with computed columns of DataGridView.in C#

When I change the value used by the computed column, the computed column is
updated only when I leave the row. I would like to update the computed
column when I leave cell (moving to another cell on the same row).

How could I do that ?
plz help .
thanx