C:C means that the whole of column C is being checked for a matching date,
and where matching the values in column D are being summed.

The & is used to concatenate the operator with the calculated date so that
SUMIF will check for values greater than that.

--
HTH

Bob Phillips

(replace somewhere in email address with gmail if mailing direct)

"F. Lawrence Kulchar" wrote in
message ...
In your reply, you stated the following: (for adding numbers within the
last
6 months in columns C and D:

=SUMIF(C:C,""&DATE(YEAR(TODAY()),MONTH(TODAY())-6,DAY(TODAY())),D:D)

IT WORKS PERFECTLY.

There are 2 items I do NOT understand.

1) the C:C and D:D references (although I can figure it out) and

2) The use of "&" -- the ambersand.

PLEASE EXPLAIN??

Thank you,

FLKulchar