3-5-3 Random, Unique Alphanumeric Code Generation

My end goal is to have an 11 digit code. We want to have a 5-digit random but unique code that will be attributed as a promo code. We then want to have 3-digit random but non-unique codes before and after the 5-digit code. We want to keep the order of number, letter, number, letter, etc.

I figured the easiest was to do this would be to have three columns with the five digit code, so we know what that is, and then combine all three columns into a fourth column.

I've added an example spreadsheet to help show the idea. I'm just trying to figure out what the easiest way to process this would be.

Thanks!

I'd use a series of RANDBETWEENs and convert them to alphanumeric equivalents. Then have a separate column to test whether the middle 5 codes are truly unique, if they are not, then do not use that code. Once you are happy with the codes generated, hard-code the RANDBETWEENs

See attach for example.

That makes sense, but my hesitance to use RANDBETWEENS is that they could eventually start making repeating codes if we start creating a large volume of them (we initially need about 6,500), so if I did that method how would I verify that the codes were unique, outside of manually checking or finding duplicates?

Hi mccodden, did you read my post in its entirety? Did you see the attached file I uploaded especially in column AD?

Then have a separate column to test whether the middle 5 codes are truly unique, if they are not, then do not use that code.

I've already addressed those issues.

Furthermore, if you're only looking for 6500 codes, the chances of randbetween getting duplicates are low as the total number of different combinations are 5,189,853,515,625. If you do get duplicates, just generate 10,000 and delete those that have been identified as duplicates.