I have two columns that I want to compare with each other. The column on the
right has extra values in it that the column on the left does not. I want to
identity the values in the right hand column that are not in the left hand
column. Like so...

(Column A) (Column B)
(Row 1) B0001 B0001
(Row 2) B0002 B0002
(Row 3) B0003 B0003
(Row 4) B0004 B0004
(Row 5) B0005 B0005
(Row 6) C0001 B0006
(Row 7) C0002 B0007
(Row 8) C0003 B0008
(Row 9) C0004 B0009
(Row 10) C0005 C0001
(Row 11) C0002
(Row 12) C0003
(Row 13) C0004
(Row 14) C0005
(Row 15) C0006
(Row 16) C0007
(Row 17) C0008

I would like to create a column C that says whether the value in column B is
in column A.

This probably sounds quite simple to you guys but I can't for the life of me
work out how to do this. It all seems to go a bit wrong on row 7 where the
same values aren't aligned with each other.

In reality this spreadsheet has thousands of rows so if I could get this
formula to work it would be a great great help to me.

Thank you so much in advance.