Issue comparing Serial Number

[tlfowler4]

So I have this spreadsheet,and I'm trying to compare Column D to F D is serial Number faults from August. F is new this month. I'm trying to look for matches on Serial numbers. I can obviously see some of them but there are over 600 from last month, and 900 for this month. How should I go about looking for the matches. I've attached the exact spreadsheet.



Faulty SER Numbers.xlsx

[Hambone70]

I did this with conditional formatting in Column D.

[newdoverman]

I added two columns to the right of your data and they are coloured yellow. The first column compares column D to column F and looks for Matches. The second column compares column F to column D for Matches. Blank cells indicate no match.