I am working on a spreadsheet for warehouse bin locations and can't get the logic down. We currently have a 4 digit and 5 digit bin system.. EX 1A2A , 1A2B , 1B2D1 , 1B2D2.
I need to clean it up to a strictly 4 digit system but my logic is already all messed up. What i am looking is for if IF cell t27 is = to 4 characters then return t27, if t27 is = to 5 characters then drop the last character. ex. 1B2D1 = 1B2D

Any help is appreciated, i didn't get very far. I immediately got stuck trying to get excel to read 4 characters