I have a big set of data that will grow over time.
I need a formula that that will do the following:
I need to add an incremental set of numbers starting at 1 and adding 1 every time column B changes set.
On top of this I need to restart the numbering every time column I changes.
But crucially, if either column B or column I matches a previous value I need to add the same number again. And if it is a new number in the sequence then add that...
Difficult to explain in words but I have attached a sample work book that hopefully makes it clear - the number in column J is what I need to replace with a formula.