Hi Steve,

If you want your SUM Formula evaluated when the Sheet1!A1 value is in
any of the worksheet arrays you could use the AND formula. Using your
previous example...

=IF(AND(ISERROR(MATCH(Sheet1!A1,Sheet2!A1:A10,FALS E)),
ISERROR(MATCH(Sheet1!A1,Sheet3!A1:A10,FALSE))),0,S UM Formula))

If you want your SUM Formula evaluated when the Sheet1!A1 value is in
all the worksheet arrays you could use the OR formula. Using your
previous example...

=IF(OR(ISERROR(MATCH(Sheet1!A1,Sheet2!A1:A10,FALSE )),
ISERROR(MATCH(Sheet1!A1,Sheet3!A1:A10,FALSE))),0,S UM Formula))

Ken Johnson