Limiting characters in one column based on text in another

Hi guys!

So I'm having a bit of an issue:

I have two columns. In column A, there is text, and it can be either "ABC" or "ABE". In column B, I will have text as well (numbers really, but I want them to be read as text, because they start with 0). I want the text in column B to have limited characters number based on the text in column A.
So, if in A1 there is "ABC", I want in B1 to be possible to only write exactly 10 characters, and if in A1 there is "ABE", I want in B1 to be possible to write only exactly 9 characters.

For now what I have done is basically half of it, which limits the character count in my selected space (B1) to exactly 10 characters when it finds the text "ABC" in A1, using data validation:

=IF(ISERROR(FIND("ABC";A1));999;10)

However when I try to add the other condition, it doesn't work. I tried adding "OR" in front of "FIND", nothing again. Maybe there is another formula altogether, but I can't recall it.

Please, help me with that

Try this as the Data Validation formula:

=LEN(B1)=IF(A1="ABC",10,9)

Hi! Thanks, however, it works only for the first half again. When there is another text, different from ABC, it still allows only 10 characters.
EDIT: I opened the table you attached and I saw it works fine, so probably I made a mistake somewhere in my table. Thank you very much again!

Maybe you didn't replace the , with ; the separator used in BG?

You're welcome.

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