Sequence a number only if another cell changes

[Chapster5]

OK real simple one I just can't think how to do it...

I have a column A which is where I want my numbering to count up

Column B has company names In

All the company names are In order but there are multiples of the same company name so:

Abc
Abc
Abc
Abc
Def
Def
Ghi
Ghi
Ghi

And so on basically I need column A to count up only if Column B changes so I need

1 abc
1 abc
1 abc
1 abc
2 def
2 def
3 ghi
3 ghi
3 ghi

If that makes sense?

Anyone able to shed some light?

Many thanks!

Nick

 

[oldbrewer]

1	abc
1	abc
1	abc
1	abc
2	def
2	def
3	ghi
3	ghi
3	ghi
	formula in A2
	=IF(B2=B1,A1,A1+1)

<colgroup><col width="64" span="5" style="width:48pt"> </colgroup><tbody>
</tbody>

 

[Chapster5]

1	abc
1	abc
1	abc
1	abc
2	def
2	def
3	ghi
3	ghi
3	ghi
	formula in A2
	=IF(B2=B1,A1,A1+1)

<colgroup><col width="64" span="5" style="width:48pt"> </colgroup><tbody>
</tbody>

Thats perfect thank you!