I want to find a formula that can validate the order number. if the future order numer entered does not start with 7****, it will show a warning. Thank you so much for your help.
https://docs.google.com/spreadsheets/d/1piS3GQ5TzrGAr4VSoSbABkMa-fRm6n_wP16RimegO6E/edit?usp=sharing