Excel list with range of values

[jakeman]

I'm working on a spreadsheet where a user enters ticket numbers for a raffle for a given customer. My data is currently in this format:

Customer	Ticket Issue Begin	Ticket Issue End	# of Tickets	Total Sale
customer 1	'001	'002	2	$40 (2 tickets @ $20 a piece)
customer 2	'003	'004	2	$40

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The problem with this format is there is room for error and the data entry person using this format can inadvertently use the same Ticket Issue Begin # or Ticket Issue End # or if the range of tickets spanned more than one ticket, some number in that range can be utilized without the user ever realizing this. I've warned the data entry user person of this and have recommended that each ticket be entered on a separate line to keep ticket #'s unique and eliminate errors. This way I could build a dynamic list of tickets that are decremented each time a number is used, so that number won't show up in the data validation list. However, the data entry user has insisted on this format.

So I'm really stuck on how to about solving for this problem and was wondering if anyone had any ideas or if someone has come across this problem before and knows a solution that worked.