I have the following in a spreadsheet:

Column A
6650
8334
2331
6650
6650
2331
6650

I want to create a function that will count Column A but do some sort of
incremental counting. This is the result I would like to achieve:

Column A Column B
6650 1
8334 1
2331 1
6650 2
6650 3
2331 2
6650 4

Please help. I have about 25,00o records and I don't want to do this
manually. I've tried =countif and other things. Please advise.

Thanks.