Hello,

My problem is as follows; in Col A I have a series of numbers and in Col B I want a unique number in Col B to align with Col A in the format of 1, 2, 3 etc as below so.. I need a formula for the following

Col A

10
20
1547251
141
10
15778212
10
20


Col B

1
2
3
4
1
5
1
2


So, every time 10 appears it is assigned the 1 and every time 20 appears it is assigned a 2 and so on and so forth.