Need help on automatic Batch wise invoice serial number

[spycein]

Hello Everyone,
I have a following Data set

Batch	Invoice No.
BT-1	ABC/01/2020-21
BT-1	ABC/02/2020-21
BT-1	ABC/03/2020-21
BT-1	ABC/04/2020-21
BT-1	ABC/05/2020-21
BT-1	ABC/06/2020-21
BT-1	ABC/07/2020-21
BT-1	ABC/08/2020-21
BT-2	ABC/11/2020-21
BT-2	ABC/12/2020-21
BT-2	ABC/13/2020-21
BT-2	ABC/14/2020-21
BT-2	ABC/15/2020-21
BT-2	ABC/16/2020-21
BT-2	ABC/17/2020-21
BT-2	ABC/18/2020-21
BT-2	ABC/19/2020-21
BT-2	ABC/20/2020-21

i am looking for a formula which would return batch wise invoice serial number as mentioned below

Serial No.	Batch	Invoice No.
1​	BT-1	ABC/01/2020-21
2​	BT-1	ABC/02/2020-21
3​	BT-1	ABC/03/2020-21
4​	BT-1	ABC/04/2020-21
5​	BT-1	ABC/05/2020-21
6​	BT-1	ABC/06/2020-21
7​	BT-1	ABC/07/2020-21
8​	BT-1	ABC/08/2020-21
1​	BT-2	ABC/11/2020-21
2​	BT-2	ABC/12/2020-21
3​	BT-2	ABC/13/2020-21
4​	BT-2	ABC/14/2020-21
5​	BT-2	ABC/15/2020-21
6​	BT-2	ABC/16/2020-21
7​	BT-2	ABC/17/2020-21
8​	BT-2	ABC/18/2020-21
9​	BT-2	ABC/19/2020-21
10​	BT-2	ABC/20/2020-21

Hope i explained my query properly.
Many thanks in advance.
Best Regards,

 

[shaowu459]

工作簿1.xlsx
	A	B	C
1	Serial No.	Batch	Invoice No.
2	1	BT-1	ABC/01/2020-21
3	2	BT-1	ABC/02/2020-21
4	3	BT-1	ABC/03/2020-21
5	4	BT-1	ABC/04/2020-21
6	5	BT-1	ABC/05/2020-21
7	6	BT-1	ABC/06/2020-21
8	7	BT-1	ABC/07/2020-21
9	8	BT-1	ABC/08/2020-21
10	1	BT-2	ABC/11/2020-21
11	2	BT-2	ABC/12/2020-21
12	3	BT-2	ABC/13/2020-21
13	4	BT-2	ABC/14/2020-21
14	5	BT-2	ABC/15/2020-21
15	6	BT-2	ABC/16/2020-21
16	7	BT-2	ABC/17/2020-21
17	8	BT-2	ABC/18/2020-21
18	9	BT-2	ABC/19/2020-21
19	10	BT-2	ABC/20/2020-21
Sheet2

Cell Formulas
Range	Formula
A2:A19	A2	=COUNTIF(B$2:B2,B2)

 

[spycein]

工作簿1.xlsx
	A	B	C
1	Serial No.	Batch	Invoice No.
2	1	BT-1	ABC/01/2020-21
3	2	BT-1	ABC/02/2020-21
4	3	BT-1	ABC/03/2020-21
5	4	BT-1	ABC/04/2020-21
6	5	BT-1	ABC/05/2020-21
7	6	BT-1	ABC/06/2020-21
8	7	BT-1	ABC/07/2020-21
9	8	BT-1	ABC/08/2020-21
10	1	BT-2	ABC/11/2020-21
11	2	BT-2	ABC/12/2020-21
12	3	BT-2	ABC/13/2020-21
13	4	BT-2	ABC/14/2020-21
14	5	BT-2	ABC/15/2020-21
15	6	BT-2	ABC/16/2020-21
16	7	BT-2	ABC/17/2020-21
17	8	BT-2	ABC/18/2020-21
18	9	BT-2	ABC/19/2020-21
19	10	BT-2	ABC/20/2020-21
Sheet2

Cell Formulas
Range	Formula
A2:A19	A2	=COUNTIF(B$2:B2,B2)

Thank you so much @shaowu459.
This is exacly what i wanted.
Best Regards,

 

[shaowu459]

thanks for you feedback