Counting rows sequentially if a certain value exists in another column

[Darnell7007]

Hello!

I am trying to count rows sequentially in column A, only if the formula COUNTIF returns a value of "1" in column B. If the COUNTIF formula returns a value of "0", I'd like column A to remain blank - or worst case, enter FALSE.
I've attached a sample of data below.

I've played around with a few formulas and ideas, but I can't get it to count sequentially, only to return a value of "1" in column A if there's a value of "1" in column B.

Sequential Count	COUNTIF
	0
	0
1	1
	0
	0
	0
2	1
	0
3	1
4	1
	0
	0
5	1
	0
6	1
	0
	0

 

[Fluff]

Hi & welcome to MrExcel.
How about either of these

Fluff.xlsm
	A	B	C
1	Sequential Count	COUNTIF
2		0
3		0
4	1	1	1
5		0
6		0
7		0
8	2	1	2
9		0
10	3	1	3
11	4	1	4
12		0
13		0
14	5	1	5
15		0
16	6	1	6
17		0
18		0
19
Data

Cell Formulas
Range	Formula
C2:C18	C2	=MAP(B2:B18,LAMBDA(m,IF(m=1,COUNTIFS(B2:m,1),"")))
A2:A18	A2	=IF(B2=1,COUNTIFS(B$2:B2,1),"")
Dynamic array formulas.

 

[jimrward]

=if(b2=1, max($a$2:a2)+1,”’)

 

[Darnell7007]

Hi & welcome to MrExcel.
How about either of these

Fluff.xlsm
	A	B	C
1	Sequential Count	COUNTIF
2		0
3		0
4	1	1	1
5		0
6		0
7		0
8	2	1	2
9		0
10	3	1	3
11	4	1	4
12		0
13		0
14	5	1	5
15		0
16	6	1	6
17		0
18		0
19
Data

Cell Formulas
Range	Formula
C2:C18	C2	=MAP(B2:B18,LAMBDA(m,IF(m=1,COUNTIFS(B2:m,1),"")))
A2:A18	A2	=IF(B2=1,COUNTIFS(B$2:B2,1),"")
Dynamic array formulas.

Hello - thank you so much for your help!

Your second formula is exactly what I needed and it's working beautifully! Have a great rest of your day!!!

 

[Fluff]

Glad we could help & thanks for the feedback.