How do you auto-fill multiple values multiple times in a single column?

I am working with an excel file that has approximately 44300 records for 13 variables. These data represent fecundity estimates for fish caught during sampling. The first variable, "number", indicates the specific number assigned to each specific fish. The second variable, "Egg", indicates the number of eggs measured during analysis. So variable A (Number) will be repeated in column A alongside the count for variable B (Egg). The number off eggs differs for every fish, so the number of times the alphanumeric will be repeated varies for each fish as well. It could go from rows 1 -130, for example. Or rows 28765-28991 etc... For every egg value of 1, I have the corresponding fish number in column A already, but it does not repeat. See the attached images for clarification if I am not explaining this well enough.

The issue I am having is that I do not currently have "number" repeated alongside the egg counts. If I attempt this by hand, copy-pasting each value into their own range of cells, it will take a very long time as there are approximately 44000 rows in this file.

Does anybody here know a way to autofill a single column in excel, but have that autofill function change every time a new number appears. IE Fill "15-C" for rows 1-154, but then change to the next number at row 155 until a new value appears in that column. Repeat until the end of the sheet.

EDIT

Find the file I am working with here: https://dl.dropboxusercontent.com/u/.../combined.xlsx

I am simply trying to complete column A in the pattern you see for the first three fish (15-C, 30-C, 32-B).

EDIT

I solved this issue using the methods found here: http://stackoverflow.com/questions/1...ill-using-that

I realize this may have been a no-brainer to some, but it was giving me trouble. Hope this helps someone in the future.

Perhaps something like this?

	A	B
2	15-c	1
3	15-c	2
4	15-c	3
5	15-c	4
6	15-c	5
7	15-c	6
8	15-c	7
9	15-c	8
10	30-c	1

B2=IF(A2="","",IF(A2=A1,B1+1,1))
copied down

I wrote that formula to return "nothing" if the respective A cell was empty (so you didnt have a bunch of numbers running down the table. As soon as you enter data into A, it should populate

It would appear that you have solved this, but for future reference (and now too, if you want), pleasae upload your file to the forum - not all members are able (or willing) to access file-hosting sites