Return Value When Option Selected [SOLVED]

I will try my best to explain what I am trying to do. It doesn't seem that complicated in my mind, but I have spent the better part of two days trying to figure this out while searching the internet for an answer.

On my main worksheet, in column A, is a drop-down list of customer names. This list is populated from a master customer list in a column on a different sheet (we'll call it the 'source sheet') in the same workbook. On that source sheet, in the column next to my customer master list, are corresponding and unique customer numbers.

I am looking for a formula that will return the customer number in column B on my main worksheet, dependent on what customer is chosen from the drop-down list in column A. Basically, I need the customer names to be "linked" to the customer numbers.

I know the basic concept can be accomplished with IF statements, but I have hundreds of customers.

Thank you in advance for any help provided.