Fill serie with exception if same number

[jellevansoelen]

Hi Excel experts,

Can someone help me with a difficult Excel question?
I think it's also difficult to explain the issue, hopefully you understand me.

I have a lot of rows with numbers, but I must number this in a serie in another cell.
But I want if the number is the same, it must be the same number in a serie.
I will let you see in a example:

Book1
	E	F
5		1986-23
6		1986-24
7		1986-25
8		1986-27
9		1986-28
10		1986-30
11		1986-31
12		1986-31
13		1986-32
14		1986-33
15		1986-33
16		1986-34
17		1986-35
18		1986-37
19		1986-38a
20		1986-38
21		1986-39
22		1986-40
23		1986-41
24		1986-42
25		1986-43
26		1986-44
27		1986-45
28		1986-46
29		1986-46
30		1986-46
31		1986-46
32		1986-46
33		1986-47
Sheet1

If you can see are some numbers the same.
When i'm go numbering in series, i get the following:

Book1
	E	F
5	1	1986-23
6	2	1986-24
7	3	1986-25
8	4	1986-27
9	5	1986-28
10	6	1986-30
11	7	1986-31
12	8	1986-31
13	9	1986-32
14	10	1986-33
15	11	1986-33
16	12	1986-34
17	13	1986-35
18	14	1986-37
19	15	1986-38a
20	16	1986-38
21	17	1986-39
22	18	1986-40
23	19	1986-41
24	20	1986-42
25	21	1986-43
26	22	1986-44
27	23	1986-45
28	24	1986-46
29	25	1986-46
30	26	1986-46
31	27	1986-46
32	28	1986-46
33	29	1986-47
Sheet1

But i want that the same numbers (1986-31, 1986-33 and 1986-46) have the same number.
So i want to get this:

Book1
	E	F
5	1	1986-23
6	2	1986-24
7	3	1986-25
8	4	1986-27
9	5	1986-28
10	6	1986-30
11	7	1986-31
12	7	1986-31
13	8	1986-32
14	9	1986-33
15	9	1986-33
16	10	1986-34
17	11	1986-35
18	12	1986-37
19	13	1986-38a
20	14	1986-38
21	15	1986-39
22	16	1986-40
23	17	1986-41
24	18	1986-42
25	19	1986-43
26	20	1986-44
27	21	1986-45
28	22	1986-46
29	22	1986-46
30	22	1986-46
31	22	1986-46
32	22	1986-46
33	23	1986-47
Sheet1

Is there somebody to help me with a formule or a script?
I hope it so much .

Tnx

 

[Fluff]

How about

=SUMPRODUCT(1/(COUNTIF(F$5:F5,F$5:F5)))

 

[jellevansoelen]

Exactly what I need.
I'm so happy with you .
Tnx!

 

[Fluff]

You're welcome & thanks for the feedback.