This will give an error message if there is not a match in AA or AB but try
putting this into C!
=CHOOSE(IF(COUNTIF(AB:AB,B1)0,0,IF(COUNTIF(AB:AB, B2)0,3,IF(COUNTIF(AB:AB,B3)0,6,IF(COUNTIF(AB:AB, B4)0,9,12))))+IF(COUNTIF(AA:AA,A1)0,1,IF(COUNTIF (AA:AA,A2)0,2,IF(COUNTIF(AA:AA,A3)0,3,12))),555, 666,777,888,999,0,111,222,333,444,1212,2323,4545)

If you need something in C1 when there is no match the equation could be
modified.
If there is always to be a match in one or both coulumns the equation can be
simplified.

"ALex" wrote:

What type of formula would respond to the following conditions 12 (excel
seems to only permit up to 7...is it possible to get around that?):

IF Any Cell in Column AA= A1 and Any Cell in Column AB =B1 then C1=555
IF Any Cell in Column AA= A2 and Any Cell Column AB =B1 then C1=666
IF Any Cell in Column AA= A3 and Any Cell Column AB =B1 then C1=777

IF Any Cell in Column AA= A1 and Any Cell in Column AB =B2 then C1=888
IF Any Cell in Column AA= A2 and Any Cell in Column AB =B2 then C1=999
IF Any Cell in Column AA= A3 and Any Cell Column AB =B2 then C1=000

IF Any Cell in Column AA= A1 and Any Cell in Column AB =B3 then C1=111
IF Any Cell in Column AA= A2 and Any Cell in Column AB =B3 then C1=222
IF Any Cell in Column AA= A3 and Any Cell Column AB =B3 then C1=333

IF Any Cell in Column AA= A1 and Any Cell in Column AB =B4 then C1=1212
IF Any Cell in Column AA= A2 and Any Cell in Column AB =B4 then C1=2323
IF Any Cell in Column AA= A3 and Any Cell Column AB =B4 then C1=4545

help me please?

Alex