Hi All.

I know how to calculate percentages. I know how to do a bit of formula stuff in Excel, but I have a simple spreadsheet which I could complicate (read: Change the entire look of the invoice) to get the result I'm looking for, but I'm hoping there's a simple formula to place in the one cell that will do it and I keep effing it up. :/

Here's the simple setup:

Column A has descriptions of items (manually typed in)
Column B has Prices of items (manually typed in)

B15 is SUM(b1:b14)

Now, A14/B14 is reserved for a discount on all items (Not being selective here.. it's all or nothing).

A14 = 10% Discount

I want B14 to show the actual amount being deducted (I.E. A negative amount) so that B15 still works correctly, and if I add an item later (To say A9/B9) B14 will auto calculate the new amount off.

Since I know how to work percentages, I've just been manually entering the discount, but I made a mistake where I forgot to recalculate the discount when I added an item. SO I've tried a few different things but it just never works out right for me. I'm missing something.

Here's a simplistic look:

A1 Widget B1 25
A2 Wudget B2 20

A14 10% Discount B14 (4.50)
A15 Total B15 40.50 (SUM B1:B14)

So, I need a formula for B14 that will SUM b1:b13, calculate the percentage off, and display the actual money being subtracted.

Thanks in advance.