Help with spreadsheet please

Verify data in 2 columns
I have a large excel file containing UK post codes (> one million rows)) in column A. In a second column (B) I have > 200 possible unverified post codes (correct format). I need to check whether those unverified post codes in column B appear in column A or not.
Is this possible. Any help really appreciated. Thanks.

you can just do

you can just do isna(vlookup(value in col2, col1, 1, 0)); true indicates that your unverified postcode does not appear in column A. does that answer your question?

Help with spreadsheet cont

Many thanks - do I insert this expression in column 3 and scroll down ?
As you can see, I am an Excel newbie.
Thanks again

Yes just put this in column

Yes just put this in column 3. assuming first unverified postcode is in cell B1 enter following in C1
=vlookup(B1,A:A,1,0) if it is present in column A it will appear in Column C as well, if not you will get #NA

Yes just put this in column

Yes just put this in column 3. assuming first unverified postcode is in cell B1 enter following in C1
=vlookup(B1,A:A,1,0) if it is present in column A it will appear in Column C as well, if not you will get #NA