Excel - running total per week

[PaulStat]

Say I have a number of entries in a spreadsheet, each entry represents a day, one of the columns for that entry represents a running total for a week. How do I calculate the running total of a specific column for a week?

Thanks,
Paul

 

[PaulStat]

But this is something I'm going to update constantly, for example below, the first column is the date, then the value for that day, then the running total for the week

07/09/09 1 1
08/09/09 2 3
09/09/09 3 6
10/09/09 4 10
11/09/09 5 15
12/09/09 6 21
13/09/09 7 28
14/09/09 1 1
...

And so on

 

[PaulStat]

But that doesn't reset it for each consecutive week though? i.e. the running total resets every monday