Hello Master Excel Gurus
I imagine this question has been asked before, but when I looked through other posts I didn't see a formula that would work for me.
I need a data validation formula for cell O8 that would only allow data entry users to enter a phone number in the format ###-###-####. For example, a phone number like 313-867-5309.
I am hoping a simple formula like =OR(ISNUMBER(o8), o8="-")) might work, but I am also open to using named ranges. I have tried the above formula and many variations of it, but with no success.
Any help would be greatly appreciated!!
Much Thanks!
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