need help with importing data from another excel file

(I hope this makes sense. I've read alot of posts on here tonight and most did not make sense to me!)

I have a spreadsheet that I use to count cigarette inventory every day. The cells are:
a1 is the price
a2 is the pack count
a3 is the carton count
a4 adds a2 and a3
a5 multiplies a4 by a1

I have about 30 different cigarette brands, so I have about 30 rows, with a cell at the bottom that gives a total dollar value of all cigarettes for day. I save the file each day using the date as the file name, ex: dec31.xls

I want to be able to see if my count today is different than it was yesterday and by how much. What I've been trying to do is insert 2 cells: one that imports the value in a4 from the prior day file and another that will calculate the difference between today and yesterday. If possible, I need this to work without having yesterdays file open. Other people will be using this file and they are not computer savvy at all. I tried pasting a link to the field in yesterdays file and just renaming todays file as "yesterday" so that tomorrow it knows where to get the data, but I need to save it each day.

Can anyone help me with the syntax to do this? I know Excel well enough to create the simple formulas used above for cells a1 thru a5, but thats about it. If it would help I can attach a copy of the file. This is pretty important because I am losing money daily in cigarettes and I need something to help track it down. Maybe one of my cashiers is stealing cigs, so I need to find out what brand I'm short in and if it's that same brand every time.

Thanks in advance for your help and Hey...Happy New Year!
truebluesubaru

I don't have a copy of the file with me. It's on my computer at work. But I will make a copy and post it later this afternoon.

Here's a copy of my spreadsheet.

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