Duplication check on 12 digit text number column

[Heretical1]

Hi all, very new to the Forum, please be patient. I am also teaching myself Excel as I go, so may have some newby questions, apologies in advance.
I have been googling like crazy so far, I do have some basic Excel knowledge, enough to get me into trouble.


My current problem is:

I am wanting my spreadsheet to highlight duplicates in 1 single column. Fairly straightforward I thought.
The column is full of numbers that are 12 digits in length, all pasted into a "text" column for ease of use and visibility (able to copy/paste into other program screens etc)
Having the column as a text field is pretty much essential at this point.

However:
sometimes the new imported data can contain 0's at the beginning, sometimes it can also contain a ' character.
I was hoping to highlight duplicates based on "the 12 digits from the right side of the cell" so that should recognise any duplicates regardless of "prefix"

Is this possible, if so how may it be done (attempting to use Conditional Formatting, but I need the formula to make it work)
I'd like to try and avoid Macros if possible, but will happily do so if there is no other way (trying to make it other-user friendly as possible)

Thankyou in advance, I hope it is an easy one for you experts out there.

 

[Momentman]

Using conditional formatting and formulas to determine which cells to format

Book4
	A
1	18462395984977
2	16340175109110
3	17500019350273
4	17685317351531
5	18857176987152
6	16228607041104
7	11079978370294
8	10612406335407
9	19668659384476
10	12184646908223
11	18343807244450
12	18646644012874
13	11570808831477
14	11845580685643
15	14831408990104
16	18511276396418
17	20462395984977
Sheet2

Cells with Conditional Formatting
Cell	Condition		Cell Format	Stop If True
A1:A17	Expression	=SUMPRODUCT((RIGHT($A$1:$A$17,12)=RIGHT($A1,12))*1)>1	text	NO

 

[Heretical1]

Thankyou so much for the quick response and simple answer.

Much appreciated.