如何使用经过数据验证的单元格计算唯一条目

I am using a userform to input into an excel cell from a data validated list. Meaning. On the userform I start typing a location and it populates the userform then the data gets put into a cell. Now the question...How can I have that column on excel count and give me the number of locations without adding in the duplicate values. Can i do it inserting a function on a cell within excel or do I need a macro of sorts. Any suggestions how I can get a function to determine the number of different locations? I searched and I am not sure if this was ever asked before. Thank you very much for your time.I am using a userform to input into an excel ce