Array Formula for unique counts

[neodjandre]

I have column A with values such as

col A col B
----------- -------------
Software SO1
Media ME1
Hardware HA1
Hardware HA2
Software SO2
Media ME2
Hardware HA3
Software SO3

I am looking to add a unique array countdown reference for each category in column B such as in the example above.

Any help would be great
thanks
Andrew

 

[Fluff]

How about

Excel 2013/2016
	A	B
1
2	Software SO1	So1
3	Media ME1	Me1
4	Hardware HA1	Ha1
5	Hardware HA2	Ha2
6	Software SO2	So2
7	Media ME2	Me2
8	Hardware HA3	Ha3
9	Software SO3	So3
1

Cell Formulas
Range	Formula
B2	=LEFT(A2,2)&SUMPRODUCT(--(LEFT($A$2:A2,2)=LEFT(A2,2)))