answer:Your problem is stated in a confusing way. If you have a list of “bogus Area Codes”, then why do you need to look anything up? You have what you want. On the other hand… let’s say that you have a list of phone numbers with Area Code, and want to look up the AC you have in a list of known ACs. In other words, let’s say that Column C (C2:C200) contains “good Area Codes”. Then, if your phone numbers (which may contain bad AC information) are in Column A (A2:A5000) you could use this formula to check if the AC appears on your “good” list or not: At D2 – or wherever else you choose – to check the entry in A2 you could enter: =if( isna( vlookup( left( A2, 3), $C$2:$C$200, 1, false)), “No Good”, “Valid”) You can copy that formula down the same column to match every number in your list of phone numbers in A:A. Caveats: 1. The Area Code information in the phone number has to be the first three characters. If you have 1-xxx- type entries, then the formula will need to be modified or the data normalized. 2. The Area Code listing has to be formatted for “text”, as the phone numbers already will be. “Text strings” won’t look up into (and match) “number” values.