try:

=SUMPRODUCT(--(MONTH($A$1:$A$50)=2)*($B$1:$B$50={"MD902","BO105 "})*($C$1:$C$50))


assuming last 6 months is data from February onwards and there is only one
year.

Or using 183 days as 6 months

=SUMPRODUCT(--($A$1:$A$50=TODAY()-183)*($B$1:$B$50={"MD902","BO105"})*($C$1:$C$50))


"AOU" wrote:

I have a spreadsheet as follows:
A B C
date MD902 40
date MD902 30
date BO105 20
date BO105 10
and so on between rows 6 to 20006

I would like to be able to produce the total of column 'C' for the last 6
month of MD902 and BO105.
--
AOU