I have 4 columns of data. Column 1 is "daily", Column 2 is the daily value,
Column 3 is "monthly", column 4 is the monthly factor.

Example:
01/01/2009 300 01/2009 0.30
01/02/2009 240 02/2009 0.20
.... ... 03/2009 0.45
02/01/2009 340
... ...
03/01/2009 450

I need help with a formula that checks the "Month" and "year" in column 1
and 3. If true then multiply column 2 and 3.

All of Jan/09 days will be multiplied by .30, all of Feb/09 will be
multiplied by .20, .....

Thanks!!