I have seen similar posts but the situation is either different or I couldn't follow the formulas that were posted so I apologize if this is redundant.

I have a [Project Number] field that is a formula numeric field.

I have a [Project Type] field with Type A, Type B, Type C

I would like [Project Number] to start at 50000 and number sequentially for Type A, start at 60000 for Type B, and start at 70000 for Type C. The tricky part is to get it to number sequentially for each type, not just based on the next [Record ID]. I don't really understand how to do a "snapshot" so I was hoping it could be explained using my situation.