Return instance number of value in an array

[noctash]

I basically want to "count up" the number of cells with value A... so the first time A appears, a 1 appears in the cell at right and so on.

Thanks in advance for any help.

 

[StephenCrump]

Here are two ways:

	P	Q	R
1
2	A	1	1
3	B
4	B
5	A	2	2
6	A	3	3
7	C
Sheet1

Cell Formulas
Range	Formula
Q2:Q7	Q2	=LET(x,P2:P7="A",IF(x,SCAN(0,x,LAMBDA(a,b,a+b)),""))
R2:R7	R2	=IF(P2="A",COUNTIF(P$2:P2,"A"),"")
Dynamic array formulas.