Array Vlookups

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All,

I want to lookup 12 columns and then add the results together, I know I
can do 12 separate vlookups and add the results but is there a more
efficient way of doing this? To complicate things I also need to
evaluate them incase one is zero or has been left blank. I was thinking
about a User Defined Function but have come unstuck in the past with
items not calculating when I want them to and as I want to give this to
quite a few people I want it as fool proof as possible.

For example, I have the months January - December and in each month I
have an item that I want to lookup and return the cost of that item to
give me an annual cost.

Hope this makes sense and thanks in advance,

James

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