Give some details about how those sheets are laid out and what data
you have in them, together with a clearer explanation of what you are
trying to do.
=IF(ISNA(MATCH(A1,Sheet2!A:A,0)),"not in list 2","present in list 2")
then copy the formula down by double-clicking the fill handle (the
small black square in the bottom right corner of the cursor) with B1
selected. It will tell you if the number is present in the second list
or not.