Conditional Counting of Rows

Hello everyone,

Can anyone help me with Conditional Counting of Rows?
So, in column A I have Job ID by rows, and in column B I have a number of rows from column A with same Job ID. What I need is a formula that would count the same Job ID by rows and put the value of counted rows in column B parallel to Job ID - better to say in the first cell where Job ID sequence starts. The rest of the rows should be null, until the new Job ID.
Thanks.

hello, popipipo

it works great, it gives me a small error but it is doing the job exactly what I need, I will pull the formula for my column and the jus copy paste the values

again thanks very much

I have one more question if you can help please, this formula work excellent, but I just remembered that I need the third column in which instead null will just be put the number of counted row from column A by Job Id, can you help with that

don't know how to set up this formula in column C, to put counted the number of rows as continuous until the next given job id is counted

the number of rows by Job Id is needed so I could solve problems with column D and E
can anyone help me whit this formula?
I have no idea how to set up this?