Adding LOOKUP to an overwrought SUMPRODUCT function

[Arlen]

I have data that looks like this on one sheet.

A | B | C

1 Date Trailer Gallons
2 Wed 02/29/07
3 66 1599
4 148 9000
5 Thu 03/01/07
6 66 8008
7 Fri 03/02/07
8 148 21398

On another sheet, using SUMPRODUCT and a static range, I am trying to
separate figures by the months in column A.

How do I add the functionality that says 'When you find Trailer 66 in Column
B, look left and up until you reach a date cell to determine if you're in the
right month?"

Please help if you can.

Arlen

 

[Wigi]

=SUMPRODUCT((cellsincolumnB=66)*(MONTH(cellsincolumnA)=1))

for January.

First, fill in the blank cells in column 1.

 

[Arlen]

Wigi,

Unfortunately, I'm dealing with hundreds of these sheets, some over 500
lines long, and the company probably doesn't want me altering the look of
their archives.

I was hoping a LOOK LEFT THEN UP(SUMPRODUCT) function on the new sheet would
serve that purpose.