Try something like this:

If only the month is significant:
=SUMPRODUCT(ISNUMBER(A1:A10)*(MONTH(A1:A10)=1))

If the month and year are significant:
=SUMPRODUCT(ISNUMBER(A1:A10)*(MONTH(A1:A10)=1)*(YE AR(A1:A10)=2006))


Does that help?

Regards,
Ron


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