Data Validation format length based on values in another cell

Hi
Would like validation set in column M based on Column H values.
In Column H values can be only "A" "B" or "C" ( have already set this as a list)

If column H value = "A" or "B" then I want the use to enter a 5digit number in column M
If Column H = "C" or blank then the user can enter any value

thanks in advance

Hello rini11, Welcome to the forum. After selecting M1, you can enter following formula
Go to data validation select custom and enter
=AND(OR($H1="A",$H1="B"),LEN($M1)=5)
Hope this helps !!
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thanks for response.
Formula works correctly if H1 = either "a" or "b" ( i can only enter 5 digit character in column M) however
when the value in column H1 = "c" it is restricting me to 5 characters also . I want to be able to enter any value
hope you can help

Try this:

DV

=OR(AND(OR($H1="A",$H1="B"),LEN($M1)=5),$H1="C")

yes - can have preceding zero's in the 5 charachters

Teethless mama - your formula works better but does not allow preceding zeros's within the 5 length

Hello Rini ! use teethless mama formula but if you want to allow preceding zeros within 5 length, then add a single apostrophe like write '00000 instead of 00000 in Cell M1 for e.g. if you wanna type following type like
Instead of
Typing Type
02345 '02345
00345 '00345
00045 '00045
00005 '00005

if answer helps click " * " (add Rep) in the left hand corner and mark thread as solved

thanks for pointing me in right direction - easier way was to format colM as text - validation now works and no need to enter leading apostrophe