adding serial number after character

[kauser]

Hello, 

i have to add a serial number after a certain character to keep them separate - 

Current Output 

Item

ABC

ABC

Expected Output - 

Item

ABC1

ABC2

i am using this following formula into formula tool but its not working 

if StartsWith([Item], "ABC") then REGEX_Replace([Item], "$1$2", "ABC") else [Item] endif

[alexnajm]

How about add a RecordId tool, then use a Formula to add them together? [Item]+ToString([RecordID])

[kauser]

yes i can but issue is Item column have lots of lines beside ABC then it will add number all of these items but i want to add number only to ABC to keep unique 

[alexnajm]

Then just add more to your Formula - IF StartsWith([Item],"ABC") THEN [Item]+ToString([RecordID]) ELSE [Item] ENDIF

[Qiu]

@kauser 
Follow the idea of @alexnajm we can do something like this.