Hi All

I am after a formula that will autofill with seqeuntial numbers based on a condition as per below.

A B
2 1
3 1
4 1
4 2
4 3
4 4
5 1
5 2
5 3
6 1
7 1


I want to autofill column B, but only to autofill if the corresponding value in A is the same.

Cheers!