create consecutive numbers on change of number

[weissihm]

I am looking for a formula or macro that can number consecutively until a number changes, then restart.
Below is sample data that I have. In column A I have customer numbers, in column B I would like a way to number them consecutively until the value in column A changes.

Column A 371663	B 1
371663	2
371663	3
371663	4
371663	5
371663	6
371663	7
372003	1
372003	2
372646	1
372646	2
375486	1
375486	2
377061	1
377061	2
378990	1
378990	2

<colgroup><col><col></colgroup><tbody>
</tbody>

 

[shg]

Welcome to the board.

Row\Col	A​	B​	C​
1​	Col A​	Col B​	​
2​	371663​	1​	B2: =IF(A2=A1, B1) + 1
3​	371663​	2​
4​	371663​	3​
5​	371663​	4​
6​	371663​	5​
7​	371663​	6​
8​	371663​	7​
9​	372003​	1​
10​	372003​	2​

 

[bbott]

Another option:

=COUNTIF($A$1:A1,A1)

Of course, this makes the assumption that numbers are sorted and not repeated further down the list.