Finding/Matching Items

In the attached example using Table B, Column B, I want to find any matching numbers in Table A Column B. If a matching number is found, I want the corresponding value in Table A Column A to be entered in Table B Column C next to the matching number.
If there is no matching number then a null value may be entered in Table B Column C (or some other character may be used: #, @, *, etc)
Thanks in advance.