Custom data validation formula

Another option:
=AND(ISERROR(--MID(A1,1,2)),--MID(A1,3,3)>0)

Hi Quang,

I was really hoping your answer would work. It needs to show false if the first two characters are not letters. I tries W31234 and it was allowed by your formula above. I think you are close to a better answer. Have another try?

Originally Posted by MarvinP

Hi Quang,
I was really hoping your answer would work. It needs to show false if the first two characters are not letters. I tries W31234 and it was allowed by your formula above. I think you are close to a better answer. Have another try?

Thhanks Marvin, it was my failure. Maybe this works:
=AND(ISERROR(--MID(A1,1,1)),ISERROR(--MID(A1,2,1)),--MID(A1,3,3)>=0)

Closer.

I tried AB123A and it was ok. I don't think it should have been accepted. I reread the problem and he wants exactly two letter and then 1,2 or 3 digits.

My formula didn't account for this second part either.