Assuming there is a date associated with each sale:

=SUMPRODUCT(--(MONTH(A2:A100)=6),B2:B100)

Column A contains Dates
Column B contains Sales

Above give sales for June (ignoring year)

=SUMPRODUCT(--(MONTH(A2:A100)=6),--(YEAR(A2:A100)=2007),B2:B100)

Above give sales for June 2007

HTH

"John cheshire lad" wrote:

I have 2 spreadsheets, one listing a list of sales, the other showing a
summary of sales by each month. how do i get the summary from the detailed
list by month.