Create a column with Concatenation of Column value + incremental value

[protocoder]

Hi Experts
Please can you let me know how to accomplish auto numbering populated ?
I can use the formula
Concatenate with . =IF(A2<>A1,1,B1+1) but unfortunately the list is not ordered based on ID I am considering. Any help? There are 100s of rows and this needs to be auto populated with protection

Input Column Expected Output

Apple Apple.1
Orange Orange.1
Apple Apple.2
Apple Apple.3
Grapes Grapes.1
Water Melon Water Melon.1
Rock Melon Rock Melon.1
Guava Guava.1
Apple Apple.4
Orange Orange.2
Water Melon Water Melon.2
Rock Melon Rock Melon.2
Orange Orange.3

help is appreciated

[bebo021999]

Try:

=A1&"."&COUNTIF($A$1:A1,A1)

[protocoder]

Thanks a lot @bebo021999.. that was quick and very helpful, I got this from other source and I confirm this is the solution. Can I put this in data validation so that no one changes it

[bebo021999]

Try to lock the sheet (menu Review/Protect sheet). Make sure those cells in column B are locked, while the rest are unlocked.