I have 2 columns of data (A and B) both with unique alphanumeric codes in
each cell (unique to each column but not between columns; ie some values are
found in both columns...these are what I need to find and mark).
I would like to know whenever a value in column B is also found in column A.
If the value in a given row in column A is found anywhere in column B, I
would like to return a 1 in the same row of column C (as where the value is
in column A). Otherwise, I want to return a blank.

Can anyone assist? I thought this might be doable with vlookup but I could
not figure out how to look for multiple #s in vlookup function...it seems to
only look for one value.