sum units sold every ten days

[Neophyte]

I have Excel 2007 and want to sum the number of units we sold every 10 days
between October 1 and December 31.
The date fields from the invoices are formated mm/dd/yyyy, the units field
is a number, and then the item description is text.
I think I can do it with sumproduct() or sumifs() but the date variable
giving me a headache. I thought about a different equation with the variable
dates in 9 cells but thought I would ask the group.
Any help is appreciated.
Lee

 

[Roger Govier]

Hi

Probably easiest to use a Pivot Table
Assuming your data has headers in row 1, place cursor in A1>Insert tab>Pivot
Table>OK
On the new sheet that appears, in the PT Field List on right of screen,
drag Date to the Row Labels
drag Description to the column Labels
drag Units to Values

Double click on any data in column A>Group>deselect Months>Select
days>select 10 as the number of Days
In the two fields at the top of the dialogue box, enter the starting and
ending dates for the period you wish to consider.