autonumber for each duplicate item without affecting when delete or filter

[Abdo]

hi experts
I want autonumber duplicates items .
what I have in column B
COST1
COST1
COST1
COST2
COST2
COST3
COST3
COST3
COST3
the result in column A should be

1 COST1
1 COST1
1 COST1
2 COST2
2 COST2
3 COST3
3 COST3
3 COST3
3 COST3
and if I delete or filter one of them shouldn't affect , just keeping the numbers

 

[cmowla]

This is a solution that requires 1 helper column C and the costs/prices are sorted (either in descending or ascending order).

Book1.xlsx
	A	B	C
1	1 COST1	COST1	1
2	1 COST1	COST1	2
3	1 COST1	COST1	3
4	2 COST2	COST2	1
5	2 COST2	COST2	2
6	3 COST3	COST3	1
7	3 COST3	COST3	2
8	3 COST3	COST3	3
9	3 COST3	COST3	4
Sheet3

Cell Formulas
Range	Formula
A1:A9	A1	=COUNTIF($C$1:C1,1)&" "&B1
C1:C9	C1	=COUNTIF($B$1:B1,B1)

 

[Abdo]

thanks
is there any way do that without helper column?

 

[cmowla]

thanks
is there any way do that without helper column?

I don't know of any way. If you had Office 365, that would be a different story. (It could be possible.)