How can i recreate event handler for each new dynamically created set of controls

we have a form that runs calculations(simple) per row on the form to provide line item totals based on the entered values.
so currently per row we calculate line totals similar to this..
protected void txtUnit12_TextChanged(object sender, EventArgs e) { txtTotal12.Text = CalcQtyUnitPrice(txtQty12.Text, txtUnit12.Text).ToString(); lblTotal.Text = CalcTotalPrice().ToString(); } and when this form was created, each row/set of textboxes had its own set of events created. Since we are now updating the form to allow the user to have new rows added for additional fields to complete, how can the above be made more general so it can be called by the newly created rows and controls. Since only 1 textbox will trigger the event at any given point, I can only get the sender that triggered it, so what can I do to make it more generic so I can just have 1 event that can be called by any of ...