What is the purpose of the double "--" in the function SUMPRODUCT?

How do I go about creating formulas with a set of given numbers and the final
total?
Ex. My numbers are 2,6,9,3 and end total is 75.  I can use any function in
the formula but it must equal 75.  I can only use the given numbers once, and

Any suggestion on this would be greatly appreciated.
I thought there was a way to overcome the limit of 7 nested IFs in the one
formula.
My worksheet is setup like this:

I find in a one column range the top value with the function
LARGE(F$1:F$23719,1)
How can i find  the reference of the cell wher this value is stored?  
thasnk you in advance ..

How would I reflect, in say in sheet2, the last amount in col B, before the
% shown
in in col B, which will change as i add new dates?
In my old 123 days to find this cell i would record a macro like goto col B,

This formula worked:
                      =IF('[ANCILLARY
2007.xls]0211-0224'!$E$4="9a-5p","ON","OFF")
I realized after I began nesting true statements that if it's possible it'd

I have managed to locate a download template that allows selection of tax if
an item is taxable... that works fine, but this template doesn't have columns
for item quantity and item price, with calculation...
It would be nice if the invoice template that comes with Excell (Office ...

I hope that makes sense. Here's what I want to do.
I have Sheet1 and Sheet2.
Sheet1 has...
        A              B             C

I'm trying to create a formula to read data from one spreadsheet and return
conditional results. I figured the IF function was best but I cannot get it
to work. I am trying to change data such as 9a-5p, 8a-4p, 6a-2p, to ON, so
the false would return OFF. Here is what I've tried ...

I need to calculate the days coverage i have for my inventory.  I start with
90660 units on 2-23 and then subtract my sales from my inventory. How many
days do i have before my inventory will go negative. I need to calulate this
daily over a period of time. Is there a formula i ...

Microsoft has an example of how to count how often multiple text values occur
by using the SUM and IF fuctions.  The example formula is:
{=SUM(IF((A2:A7="Buchanan")+(A2:A7="Dodsworth"),1,0))}
Copying and pasting the sample table and formulas work fine - since array

For my school project i need to produce histograms of a varied range
of estimates. I have attempted to produce the histogram using the
histogram tool yet i need to use this set of interval:
INTERVAL

I would like to know how many working days between 2 dates. BUT, the
networkdays function only takes into account SATURDAYS and SUNDAYS as week
end.
I live in a country where week ends are FRIDAYS and SATURDAYS...

I work for a transportation company. On a spreadsheet, I have a list of
Shippers, beside that, I have a list of unique SKUs that the coresponding
shipper carried. Beside that, I have the coresponding Bill of Lading (BOL)  
that the Carrier took that SKU out on. I need to count how ...

i need to insert a row with the date into a pivot table.  any ideas?  please
help!