Hi

I have a workbook which has 12 columns identified by months.

Each month has a different value. What I need to do is to have a defined
cell that represent the number of weeks in the Fiscal year for sales.

If the weeks equals 4 I will use the figure in Jan but when the week equals
5 I need to use the January and February numbers. I don't really want to
create an additional 12 columns to do this calculation.

Is there a formula for a tier calculation to have it add together all the
weeks?

Thanks