Total of text boxes in GridView

Total of text boxes in GridView

I have grid view (.net 3.5) that has hours fields where user can enter hours information for a week, with other controls. There is text box that shows Total for the individual days:

Day1TextBox, Day2TextBox, Day3TextBox, Day4TextBox, Day5TextBox, Day6TextBox, Day7TextBox AND TotalHours.

User can edit hours for days while TotalHorus is readonly.

When user changes the hours i need to show updated total hours in text box TotalHours.

TotalHours = Day1TextBox + Day2TextBox + Day3TextBox + Day4TextBox + Day5TextBox + Day6TextBox + Day7TextBox;

Any help is apprecialted.

Thanks
Vijay