This should be an easy one...

In column A I want to have a counter or series that only changes to the next value when the value in a separate column changes.

If column B is the order number, I want cell A2 to begin with a value of 1 and only move to a value of 2 when the order number changes. it would look like this

Counter Order # Product #
1 12345 65478
1 12345 52145
1 12345 65214
2 65252 98547
2 65252 65298
3 98765 96745
3 98765 63756
3 98765 12856

Thanks in advance for the help

Scott