Assuming your data starts in Row 1, put this formula in D1 and copy it
down...

=SUMPRODUCT(MAX((A$1:A$1000&B$1:B$1000=A1&B1)*C$1: C$1000))

Change all the 1000's to a row number that will be larger than the largest
row number you ever expect to put data in.

--
Rick (MVP - Excel)



"Nadine" wrote in message
...
I have a file in Excel 2003. In 1 column I have a numeric field. In the
next column I have a 2 digit apha field. In the third column I have
another
numeric field. For each row I need a formula in the 4th column.

All columns can have duplicate numbers/characters. What I need to do is
find the largest number if column 3 for the unique combination of columns
1
and 2.

Example:
Col A Col B Col C Col D (to be reult is shown - need
formula)
12345 AA 1 5
12345 AA 1 5
12345 AA 2 5
98765 BA 2 2
98765 BA 1 2
12345 AA 5 5
98765 BA 2 2

Thank you.