Unique IDs count in different months

[kpontarollo]

I need help figuring out an easier way to do this. I need to count unique ideas per month, but with a caveat:

If there are 50 Unique IDs in January. I need to exclude any of those IDs that appear in February before I take a unique count of IDs in February. In march, I would have to exclude the unique IDs that appeared in both January and February. 

Essentially:

If I, KP, appear in January, I should not be included in February. So if there was KP and DK in February the unique count of February would 1 not 2 because I was already counted in January.

HELP!!!!

[atcodedog05]

Hi @kpontarollo 

Can you provide some sample input and expected output It will help us get a better understanding of the usecase.

We will be happy to help : )

[kpontarollo]

Yes.

January INPUT: A, B, C, D, E, F, G 

January Output: 7 Unique Letters

February INPUT: A, B, C, D, X, Y, Z

February Output: 3 Unique Letters (because A, B, C, D need to be excluded because they were included in January.

March INPUT: A, B, C, D, W, X, Y, Z

March output: 1 Unique Letter (Because all the others were counted in previous months)

I currently have something to do this. However, the set up is very manual so I need a better way to do this as I need it for 24 months.

Does this make sense? Thank you SO Much for your help!

[atcodedog05 · Accepted solution]

Hi @kpontarollo 

Here is how you can do it.

Workflow:

Hope this helps : )

[kpontarollo]

This is amazing! Thank you so much!

[atcodedog05]

Happy to help : ) @kpontarollo 

If my response helps please don't forget to mark it as solution.

Cheers and have a nice day!